B/o/r?edf 

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I9Q5 


THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 

Gift  of 


Dr.  C-ustav  F.  Ruediger 


WORMIAN    BONES 


OHARIjES    A.f  PARKER,    M.    D, 

INSTRUCTOR    IN  8TJRQERY  AND  IN  -A.NA/POMY,  RtlSH  MBDIOAL  Cor.r.EGB, 

IN  AFFILIATION  A^TTH  THE  UNTVBRS TTY  OF  CHIOACJO 


f 

WORMIAN    BONES 


CHARLES    A.    PARKER,    M.    D., 

INSTRUCTOR  IN  SURGERY  AND  IN  ANATOMY,  RUSH  MEDICAL  COLLEGE, 
IN  AFFILIATION  WITH  THE  UNIVERSITY  OF  CHICAGO 


CHICAGO 
ROBERTS    PRESS 

1D05 


CONTENTS. 


PAGE 

DEFINITION 5 

SYNONYMS 5 

HISTORY 5 

Letter  of  Olaus  Worm,  establishing  claim  to  priority G 

Others  mentioned — Hippocrates,  Paracelsus,  Vesalius,  Guin- 

ter  d'Andernach,  Goethes 7 

CLASSIFICATION 8 

Pozzi's— True  and  false — suturaux,  fontanellaires,  and  insu- 

laires 8 

GENERAL  FEATURES— Structure,  shape,  size,  sutures 8 

FREQUENCY  AND  SITE 9 

Frequency  in  infants,  apes,  and  in  pathological  conditions...  9 
Table  based  on  Chambellan's  observations  on  485  skulls,  show- 
ing size,  number  and  location  per  hundred  skulls 11 

Greatest  frequency  in  lambdoid  suture 12 

Increased  frequency  in  coronal  suture  in  artificially  deformed 

skulls 12 

Almost  entirely  limited  to  sutures  bordering  parietal  bones.  13 

Rare  varieties  and  unusual  sites.    Os  antiepilepticum 13 

DEVELOPMENT 17 

Development  of  membrane  bones 17 

Two  modes  of  origin 17 

Time  of  appearance  18 

Frequent  in  fetal  crania 18 

May  be  synchronous  with  earliest  centres 19 

Diminish  with  obliteration  of  sutures 20 

FUNCTION — Supplementary  to  regular  bones 20 

MORPHOLOGY . .  20 

Low  morphological  value  of  membrane  bones 20 

Development  of  occipital  bone 21 

Os  interparietal 23 

Os  Inca 24 

Os  epactal 25 

ANTHROPOLOGICAL  SIGNIFICANCE 26 

Relation  between  number  of  Wormian  bones  and  cubage  of 

cranium — comparative  tables 26 

Dextral  preponderance 27 

Relation   of  sutural  length  to  cranial  capacity— increase  of 

one  accompanied  by  increase  of  the  other 28 

Greater  dextral  sutural  length 28 

Incidental.    Variations  in  transverse  and  squamous  sutural 

lengths  in  different  types  of  skulls 28 

Relation  of  jaws  to  cranial  types 29- 


4  CONTENTS 

PAGE 

CAUSES  ..............................................................  29 

Usually  of  physiological  origin  ...............................  29 

Pathological  —  Severe  dyscrasiae,  fetal  or  maternal,  degenera- 

tive influences,  possibly  a  few  specific  diseases  ..........  29 

Relative  importance  of  pre-  and  postnatal  influences  .........  30 

Author's  case  unique,  showing  characteristics  of  both  osteo- 

genesis    imperfecta    and     chondrodystrophia     felalis. 

Changes   in  face  distinctly  degenerative  in  type.    No 

maternal  dyscrasia  known  ..............................  31 

MEDICAL  ASPECTS  —  Very  limited  .....................................  32 

Possibility  of  causing  confusion  in  fractures.  Saucerotte'u  case.  32 
Influence  on  childbirth.  Three  cases  of  pathological  influence 

—  only  ones  recorded  in  literature  .......................  32 

AUTHOR'S   CASE    OF    EXTRAORDINARY     DEVELOPMENT   OF    WORMIAN 

BONES. 

GENERAL  DESCRIPTION  OF  SKULL  ...................................  33 

Origin,  shape,    measurements,  capacity,   cephalic  index,   class, 

structure  .................................................  34 

BASE  —  Measurements,    development,    comparison    with    normal 

skull,  absence  of  premature  ossification  and  shortening.  35 

Asymmetry,  slight,  no  important  mensural  variations.  .  .  ........  35 

SPECIAL  FEATURES  ...................................................  35 

RECESSION  OF  FACE  .............................................  35 

Comparison  of  profiles  —  vertical  and  horizontal  ...............  35 

Cause  —  Imperfect  development  of  jaws  ..............  .........  36 

Jaws  and  dentition  ...............................  ............  37 

Superior  maxilla1  —  Dentition  incomplete  and   asymmet- 

rical with  deformity  .................................  37 

Mandible  —  Dentition  incomplete  and  asymmetrical  with 

deformity  .............................................  37 

POSTERIOR  NARES  —  Infantile  in  type  ...........................  38 

WORMIAN  BONES  .................................................  39 

Number,  172  ..................................................  39 

Location  and  area  involved,  base  free  ........................  39 

Size,  shape,  and  other  characteristics.    The  one  in  the  frontal 

the  largest  true  Wormian  bone  yet  recorded  ............  39 

Separate  bones  involved  —  limited  to  membrane  bones  .........  39 

Distribution  by  number  in  different  regions  ..................  40 

Sutures  involved  —  adventitious  sutures  ......................  40 

Fontanelles  —  rare  occurrence  in  fontanelle  orbitaire  ..........  41 

PRESERVATION  OF  CRANIAL  ANLAGE  ................................  42 

REPORTS  OF  OTHER  CASES  ...........................................  42 

GENERAL  SUMMARY  ............................  .....................  44 

CHAMBELLAN'S  CONCLUSIONS  .............................  .......  44 

H  YRTL'S  RULES  ..................................................  44 

AUTHOR'S  CONCLUSIONS  ..........................................  45 


BIBLIOGRAPHY. 


WORMIAN     BONES. 


CHAELES    A.    PARKER. 


DEFINITION. — Wormian  bones  may  be  defined  as  those  accidental  or 
intercalated  bones  found  in  the  cranium  having  no  regular  relation  to  its 
normal  ossific  centres.  They  are  of  frequent  occurrence  in  man,  and 
generally  occupy  the  sutures.  In  other  animals  they  occur  with  much 
greater  rarity. 

SYNONYMS. — According  to  discoverer,  ossicula  Andernaci,  ossa 
G-oethiano;  shape,  ossa  triquetra,  ossa  triangularis,  ossa  quadratum:  loca- 
tion, suturaux,  fontanellaires,  insules,  intercalaria,  raphogeminantia, 
apicis;  function,  complementaria,  ossa  accessorii. 

Schaltknoclien  and  Nahtknochen  are  the  terms  in  common  use  by  the 
German  writers,  while  the  French  writers  have  occasionally  called  them 
clefs  de  route,  or  "keys of  the  vault." 

One  occupying  the  upper  part  of  the  occipital  bone,  the  subject  of 
considerable  controversy  among  the  anthropologists  of  the  latter  part  of 
of  the  last  century,  is  frequently  alluded  to  as  the  os  epactal,  or  os  Inca. 
The  latter  name  originated  with  the  description  of  Tschudy,  who,  with 
Rivero,  considered  it  a  special  racial  characteristic  of  the  ancient  Peru- 
vians— a  contention,  however,  that  was  soon  completely  refuted  by  the 
larger  observations  of  Jacquart,  showing  its  more  comprehensive  generic 
value,  and  its  occurrence  in  others  than  the  Incas,  and  its  very  frequent 
absence  in  the  race  of  which  it  was  supposed  to  be  characteristic. 

HISTORY. 

Occurring  so  frequently,  and  often  of  considerable  size,  they  were  no 
doubt  noticed  by  many  observers  long  before  we  had  specific  accounts  of 
them.  The  first  special  description  we  have  of  them  is  by  Olaus  Worm, 
a  Danish  anatomist,  1588-1654,  who  described  them  at  some  length  in  a 
letter  to  Thomas  Bartholin. 

In  turn  Bartholin  named  them  Ossa  Wormiana,  their  present  name. 
As  this  letter  is  of  historical  importance  in  establishing  the  author's 
claim  to  priority  of  description  it  is  introduced  into  evidence  here.  The 


6  CHARLES    A.    PARKER 

few  prefatory  and  closing  remarks  are  of  course  not  relevant  here,  but 
the  complete  text  is  given  to  avoid  mistakes  that  have  occurred  in  partial 
transcriptions. 

Thomae  Bartholini  epistolarum  medicinalium,  a  doctis  vel  ad  doctos 
scriptarum,  centuria  1.  Hagae  Comitum,  apud  PetrumGosse,  bibliopolam, 
MDCCXL.  9  1.,  416  pp.  sm.  8.  pp.  122-124. 

EPISTOLA  XXIX. 

De  ossiculis  in  sutura  lambdoidea. 

Thomae  Bartholino.  Patavium. 

Librum  tuum  de  Luce  Viventium  videndi  maximp  teneor  desiderio. 
Omnibus  innatum  lumen,  unde  ortum  trahat,  cur  se  in  tarn  paucis  pro- 
dat,  scire  gestit  animus.  Cocui  historiam  eleganter  tradidit  Moufettus 
in  Theatre  Insectprum  lib.  I.  cap.  15.  quern  si  consulueris,  invenies  quas 
ad  rem  faciant:  etiam  de  liquore  ex  iis  praeparato,  noctu  lucente.  Cum 
Lugduni  Batavorum  adhuc  haereres  &  Anatomiae  Parentis  editionem 
meditareris,  de  ossiculis  lambdoideis  me  tibi  scripsisse  memini;  sed  quia, 
quae,  turn  exarabam,  excidisse  videntur.  jam  repeto,  modo  usus  alicujus 
esse  possunt.  Anno  1628.  cum  frequent!  auditorum  coronas  ossa  sceleti 
humani  demonstrarem  atque  exponerem;  in  ipsa  sutura  lambdoidea 
ossicula  sex  inveni,  quae  utrumque  tabulatum  cranii  perforabant,  a 
nemine,  quod  sciam,  ante  animadversa.  Diversissima  enim  sunt  ab  iis, 
in  quas  os  ipsum  quandoque  dispescitur,  quod  sutura  lambdoidea  circum- 
scribitur,  Triquetra  quibusdam  dictis.  Tria  in  dextro,  totidem  in  sinis- 
tro  ejus  extant  ductu,  magnitudine,  figura  &  situ  discrepantia.  Infimum 
ad  processum  mamillaremconspicitur,  medium  paulosuperius,  vixdimidii 
digiti  intervallo,  tertium  aliquanto  longius  a  secundo  distat.  Figura 
sunt  varia,  triquetra,  oblonga,  ovalia.  In  sinistro  ductu  majora  omnia 
apparent,  quam  in  dextro.  Maximum  unguem  pollicis  non  excedit.  In 
concava  cranii  superficie  distincte  magis  quam  in  convexa  apparent, 
quocirca  ablata  calvaria  melius  observantur.  Ut  omnia  sint  clariora, 
iconem  addo.  A.  portio  est  sutune  sagittalis.  B.  sutura  lambdoidea.  C. 
sectio  serra  facta.  D.  primum  os  sinistri  ductus.  E.  secundum.  F.  ter- 
tium. Gr.  primum  dextri  ductus.  H.  secundum.  I.  tertium.  K.  mag- 
num cranii  foramen,  per  quod  medulla  in  spinam  descendit.  LL.  Pro- 
cessus  mammillares.  Dissimulare  interim  hie  nequeo,  in  diversis  craniis, 
tarn  numero,  quam  magnitudine  &  figura,  item  situ,  variarehaec  ossicula. 
Dum  haec  scribo,  mihi  ad  manum  quinque  sunt  crania;  quorum  duo 
suturam  sagittalem  per  qs  frontis  in  nasum  usque  protendunt.  Horum 
alterum,  quatuor  saltim  istorum  ossiculorum  ostentat,  atque  ex  iis  unum 
in  ipsa  junctura  sagittalis  cum  lambdoidea,  quo  in  loco  Triquetrum  dic- 
tum, conspici  solet:  in  altero  vero  duo  saltim  extant,  eaque  in  dextro 
ductu  tantum.  Verum  haec  crania  integra  erant;  si  calvariam  auferre 
licuisset,  forsan  plura  ostendisset  interior  superficies.  Sed  cum  Naturam 
in  pssibus  majoribus,  suturis  ipsis,  &  aliis  humani  corporis  partibus, 
varie  ludere  videamus,  quid  mirum  si  in  hisce  antiquum  obtineat?  In 
monumentis  ac  sepulchris  majorum  nostrorum  licet  res  varias  reperian- 
tur,  ut  lib.  1,  cap.  7.  Monumentorum  nostrorum  docuimus,  lucernarum 
tamen  perpetuarum  nulla  prorsus  vestigia.  Inter  veterum  inventa 
deperdita  eas,  ni  fallor,  refert  Pancirollus,  qui  de  iis  ex  professo  agere 
videtur.  Vale  &  bono  publico  feliter  vive.  Hafniae  6,  April,  1643. 

T.  T. 

Olaus  Worm  D. 


WORMIAN    BONES  7 

Of  the  earlier  mention  of  these  bones,  Sappey  refers  to  Hippocrates, 
but  does  not  cite  the  instance,  and  a  very  careful  search  by  the  writer 
through  all  of  the  accessible  editions  of  the  works  of  that  celebrated 
teacher  fails  to  establish  the  claim  of  his  priority.  It  is  true  he  deals 
with  bones  and  sutures,  and  even  mentions  in  his  fifth  book  of  The 
Epidemics  the  case  of  Autonomus  of  Omilos,  wherein  he  mistook  a  frac- 
ture near  the  bregma  for  a  suture — not  a  suture  for  a  fracture — with  a 
fatal  result  because  of  delay  of  proper  treatment.  He  explains  his  error 
in  diagnosis  as  being  due  to  the  proximity  of  the  fracture  to  the  known 
sutures  of  that  region,  and  in  another  place  warns  against  the  possibility 
of  such  mistakes  being  made  in  the  neighborhood  of  sutures,  but  in  no 
way  can  this  be  construed  as  an  instance  of  an  adventitious  suture  or  an 
intercalated  bone. 

Eambaud  and  Renault,  in  their  work  on  the  "Origin  and  Develop- 
ment of  Bones,"  mention  Gonther  d'Andernach,  or  as  his  biographer,  E. 
Turner  calls  him,  Jean  Guinter  d'Andernach,  a  German  anatomist, 
1487-1574,  as  having  "discovered  the  os  Wormiens,  and  Olaus  Wormius 
gave  their  name." 

Testut  says  Tourtefois  claims  that  both  Andernach  and  Vesale,*  the 
•celebrated  Belgian  anatomist,  of  1514-1564,  gave  good  descriptions  of 
them,  particularly  in  relation  to  their  medical  importance  in  cerebral 
affections,  epilepsy,  etc.  Hence,  the  designation  ossicula  Andernaci  as 
one  of  the  synonyms  mentioned  by  Hyrtl. 

This  latter  author  also  says  Paracelsus,  1460-1541,  mentioned  the  one 
in  the  posterior  fontanelle,  which  was  called  the  ossiculum  Antiepilep- 
ticum,  on  account  of  its  supposed  relation  to  epilepsy. 

These  three  teachers  were  contemporary  in  the  first  half  of  the  16th 
century. 

Yet  again,  Peckham,  in  the  "Reference  Handbook  of  the  Medical 
Sciences,"  says  Fischer  credits  an  account  preceding  Worm's  to  one 
Goethes,  in  an  article  "De  ossa  epactala  seu  Goethiana,"  Moscow,  1811. 

Still,  it  is  evident  that  Worm's  careful  observations  entitle  him  to 
the  same  distinction  of  practical  priority  that  Columbus'  voyage  does 
that  worthy  mariner  to  the  discovery  of  America,  though  neither,  in 
point  of  fact,  was  actually  first  in  his  respective  claim. 


*Zeller  mentions  Vesalius  as  having  found  the  squama  occipitalis  divided  In  two 
parts  by  the  continuation  of  the  sagittal  suture  from  the  lambda  to  the  foramen  mag- 

niim.     Thfl  a*rp  wa.K  not,  iriv^n 


num.    The  age  was  not  given. 


CHARLES    A.    PARKER 


CLASSIFICATION. 

Pozzi,  in  the  Dictionnaire  Encydopedique  des  Sciences  Medicales. 
divides  the  Wormian  bones  into  two  main  groups,  the  false  and  the  true, 
the  former  including  those  resulting  from  anomalous  development  of 
normal  centres,  as  double  parietals,  double  squamosals  and  interparietal 
bones,  the  os  supplementaires  of  Manouvrier,  the  latter,  the  os  inter- 
calaires,  the  variety  usually  observed,  comprising  those  having  no  such 
relation  to  the  regular  ossific  centres,  and  usually  situated  along  the 
margins  of  the  bones  in  the  sutures  and  fontanelles,  suggesting  their 
further  division  into  os  suturaux  and  os  fontanellaires.  To  these  Ma- 
nouvrier  adds  a  third  variety,  the  os  endocraniens,  or  insules,  of  Hyrtl. 
This  division  of  the  true  Wormian  bones  into  three  classes,  suturaux, 
fontanellaires  and  insules,  or  endocraniens,  is  followed  by  Porier  et  Char- 
pey,  Testut,  Debierre  and  others. 

Os  endocraniens  are  usually  small  isolated  fragments  occurring  exclu- 
sively in  the  inner  table,  and  are  designated  by  position  as  endofrontal 
and  endoparietal,  etc. 

They  are  also  called  insular  or  peninsular  according  as  they  are  com- 
pletely enclosed  in  a  bone  or  are  contiguous  to  a  suture.  Manouvrier 
found  endofrontal  bones  15  times  in  the  crania  of  58  Parisians,  and  Hyrtl 
describes  them  in  the  parietal  bone  near  the  squamous  margin.  They 
have  also  been  mentioned  by  Zermak,  Henle  and  others. 

Pozzi  divides  the  os  fontanellaires  into  the  following  obvious  classes 
named  in  the  order  of  frequency  of  their  occurrence,  the  normal  fonta- 
nelles preceding  the  abnormal,  or  infrequent  ones,  described  by  Hamy. 

Normal.    Os  Wormien  fontanellaire  asterique, 
Os  Wormien  fontanellaire  pterique, 
Os  Wormien  fontanellaire  lambdatique, 
Os  Wormien  fontanellaire  bregmatique, 
Os  Wormien  fontanellaire  orbitaire,  at  the  junction  of  the 
frontal,  os  planum,  and  lesser  wing  of  the  sphenoid. 

Abnormal.    Os  Wormien  obelique — at  the  obelion. 

Os  Wormien  glabellaire — at  the  glabella. 

To  this  last  class  Hrdlicka  adds  a  group  occupying  the  sites  of  the 
somewhat  numerous  primary  fissures,  occasionally  remaining  as  super- 
numerary fontanelles  in  the  margins  of  the  developing  parietal  bones. 

GENERAL    FEATURES. 

In  structure  Wormian  bones  resemble  the  other  bones  of  the  cranium 
and  involve  both  the  external  and  internal  layers,  but  not  infrequently 
they  are  limited  to  the  outer  layer  only,  much  more  rarely,  as  the  os 
insules,  to  the  inner. 


WORM  i AN    BONES  9 

They  articulate  with  the  surrounding  bones  by  sutures,  the  denta- 
tions of  which  are  more  complex  on  the  outer  than  on  the  inner  surface 
of  the  skull. 

In  shape  they  are  round,  oval,  oblong,  triangular,  quadrilateral  and 
polygonal,  and  they  vary  in  size  from  less  than  a  millimeter  in  diameter 
to  the  one  measuring  5  by  9  cm.  in  the  skull  presented  by  the  author  at 
the  close  of  this  article,  the  largest  true  Wormian  bone  whose  measure- 
ments were  obtainable,  although  the  false  Wormian,  or  interparietal 
bone,  may  even  considerably  exceed  this. 

Quain  says,  '-They  may  exceed  an  inch  in  diameter'1:  John  and 
Charles  Bell,  that  "they  are  sometimes  full  size  of  a  crown":  Ilyrtl, 
that  they  "vary  in  size  from  a  flaxseed  to  a  dollar":  Zeller,  "from  the 
size  of  a  lentil  to  two  inches  or  more":  Merkel,  that  they  "vary  in  size 
even  to  the  upper  half  of  the  occipital";  and  Gruber  reported  one  in  the 
anterior  fontanelle  measuring  5  cm.  by  6.5  cm. 

FREQUENCY    AND    SITE. 

The  number  of  Wormian  bones  varies  in  different  classes  of  skulls, 
and  in  different  parts  of  the  same  skull,  according  to  apparently  well 
established  laws.  In  this  connection  a  synoptic  study  of  the  unique  and 
comprehensive  tables  of  Chambellan  is  of  the  greatest  interest. 

Victor  Chambellan,  to  whose  inaugural  thesis  reference  has  already 
frequently  been  made,  who  studied  Wormian  bones  both  from  an  anthro- 
pological and  an  anatomical  standpoint,  gives,  in  his  extensive  tables 
arranged  from  the  examination  of  widely  diversified  groups  of  human  and 
simian  skulls,  the  size,  location  and  number  of  Wormian  bones  in  the 
several  groups  of  the  series,  and,  by  clever  comparisons  and  contrasts, 
establishes  quite  definite  laws  in  regard  to  the  relative  frequency  of  their 
occurrence. 

The  following  groups  were  comprised  in  his  observations: 

Auvergnats ...  Males   56      Females 47 

Parisians "     124  "        56 

Neo-Caledonians "       46  "        tt 

Negroes "       89  "        11 

Incas "      44  "        (> 

TOTAL 485 

Foetuses 10 

I  nf ants  12  months  or  less 14 

Infants  2  years 1 

Microcephales 5 

Hemi-microcephales 15 

Hydrocephales,  adults 13 

Hydrocephales,  foetuses,  infants  of  several  months,  one  5  years 8 

Apes,  anthropoid 52 

Apes,  inferior 73 


10  CHARLES    A.    PARKER 

Tor  the  purpose  of  determining  the  sites  of  predilection  and  relative 
numbers  and  sizes  in  different  regions,  the  data  from  the  485  normal 
adult  human  skulls,  male  and  female,  are  here  condensed  from  Chambel- 
lan's  separate  catagories  into  one  general  table  arranged  in  decreasing 
order  of  their  frequence.  No  attempt  is  made  to  separate  the  male  from 
the  female  skulls,  nor  those  of  different  races. 

The  size  is  designated  by  the  nomenclature  of  Broca,   which  is  as 
follows: 
No.  1  comprises  all  those  bones  which  measure  from  1-2  mm.  in  their 

smallest  diameters. 
No.  2  comprises  all  those  bones  which  measure  from  3-5  mm.  in  their 

smallest  diameters. 
No.  3  comprises  all  those  bones  which  measure  from  6-10  mm.  in  their 

smallest  diameters. 
No.  4  comprises  all  those  bones  which  measure  from  10-20  mm.  in  their 

smallest  diameters. 
No.  5  comprises  all  those  bones  which  measure  over  20  mm.   in  their 

smallest  diameters. 

For  example,  if  the  sagittal  suture  of  a  skull  contain  four  Wormian 
bones  measuring  1.5  mm.  in  their  smallest  diameters,  and  two  3.5  mm. 
in  their  smallest  diameters,  they  would  be  designated,  Sagittal  suture, 
4  (1),  2  (2).  To  these  Chambellan  has  added  the  designation,  +1  (plus  1), 
for  those  bones  less  than  a  millimeter  in  their  smallest  diameters,  but 
which  he  thinks  should  be  recorded  in  an  exhaustive  study. 

Furthermore,  as  the  number  of  skulls  examined  varied  in  the  different 
races  and  sexes,  the  results  were  originally  given  for  each  group  in  terms 
of  100  skulls  for  purposes  of  ready  comparison,  a  method  which  for  the 
same  practical  reason  will  be  made  use  of  here. 


WORMIAN    BONES 


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Table  showing 
estimated  from  a 
their  numerical  fre 

Lambdoid  suture,  rigl 
Lambdoid  suture,  left 

Coronal  suture,  right 
Coronal  suture,  left..  . 

Mastoparietal,  right.. 
Mastoparietal,  left  .  .  . 

Asterion,  right  
Asterion,  left  

Pterion,  right  
Pterion,  left  

Squamoparietal  sutur 
Squamoparietal  sutur 

Sagittal  suture  

Masto-occipital  sutun 
Masto-occipital  sutur^ 

a 
I 

•*j         * 

"Sfi     3 

-*-*    1 
II     c 
OO    S 

Sphenofrontal  suture, 
Sphenofrontal  suture, 

Obelion  
TOTAL  

12  CHARLKS    A.    PARKER 

The  greatest  frequency  of  Wormian  bones  in  the  lambdoid  suture  is 
attested  by  all  observers:  containing  as  it  does,  with  the  addition  of  the 
asterion  and  masto-occipital  sutures,  as  its  continuations,  271.12  bones, 
or  one-half  of  the  whole  number  present  in  all  the  skulls.  Hyrtl  observed 
300  in  this  suture  in  the  skull  of  a  cretin,  the  largest  number  found 
recorded  in  a  single  skull.  Liston  reported  100  in  a  hydrocephalic  skull, 
but  no  reference  is  given  of  the  sutures  involved.  That  the  coronal 
suture  should  stand  second  as  a  site  of  predilection  for  these  bones  in 
normal  skulls  is  a  source  of  some  surprise,  as  this  region  is  not  usually 
considered  as  specially  favoring  their  existence  (Humphrey),  though 
Dorsey  has  particularly  remarked  their  increased  frequency  in  this 
suture  in  artificially  deformed  skulls.  Sandifort  observed  them  in  this 
suture. 

Hrdlicka  distinguishes  a  number  of  the  Wormian  bones  occurring  in 
the  sutures  surrounding  the  parietal  as  fontanelle  in  origin,  and  else- 
where their  frequency  is  given,  but  no  other  statistics  based  upon  such 
a  distinction  are  available. 

In  an  illustrated  article  entitled  "Wormian  Bones  in  the  Artificially 
Deformed  Kuaikuitl  Crania,"  appearing  in  the  American  Anthropologist 
for  June,  1897.  Dorsey  comments  upon  the  frequent  occurrence  of  Worm- 
ian bones  in  the  coronal  sutures  of  the  deformed  skulls  of  this  race. 

They  were  found  10  times  in  60  skulls,  occurring  rather  more  fre- 
quently in  females  than  in  males,  and  oftener  on  the  left  side  than  on 
the  right.  In  one  case  there  were  5  bones  on  the  right  side,  and  2  on 
the  left. 

With  this  article  in  mind  an  analysis  was  made  of  the  cases  in  the 
museum  of  the  Royal  College  of  Surgeons,  England,  given  in  the  cata- 
logue of  1879,  Part  I. 

Total  number  of  crania  mentioned,  1010. 

Total  number  mentioned  as  having  Wormian  bones,  79,  including 
cases  of  epactal  and  epipteric  bones. 

Number  containing  Wormian  bones  in  coronal  suture,  15. 

Further  analysis  of  these  15  showed  the  following: 

They  occurred  9  times  in  males,  once  in  a  female,  and  5  times  in 
crania  of  unknown  sex,  some  being  children.  They  were  present  on  the 
right  side  in  14  cases,  on  the  left  in  10,  and  on  both  sides  in  8.  Their 
numbers  were  not  given  frequently  enough  for  study. 

In  20  skulls  of  flat  head  Indians,  7  contained  Wormian  bones,  and  in 
5  they  occurred  in  the  coronal  sutures,  the  frequency  of  occurrence  in 
this  suture  being  71  per  cent,  of  the  skulls  containing  these  ossicles. 
Taking  out  these  5  cases  from  the  special  total  of  15,  and  the  7  cases 
from  the  general  total  of  79,  there  remain  10  examples  of  coronal  occur- 
rence in  72  cases  of  Wormian  bones,  a  frequency  of  14  per  cent.  A  com- 


WORMIAN    BONES  13 

parison  of  the  71  per  cent,  of  frequency  in  the  flat  heads  with  the  14  per 
cent,  in  other  skulls  shows  the  predilection  of  this  site  in  the  former  to 
be  five  times  as  great  as  in  the  latter. 

In  explanation  of  this  striking  peculiarity  Dorsey  says,  "These  skulls 
are  deformed  by  bandages  and  flattened  in  front,  projecting  behind, 
often  showing  a  groove  just  behind  the  coronal  suture  from  the  bandages 
*  *  *  *  They  are  probably  due  to  elongation  of  the  skull,  and  con- 
sequent faulty  union  of  the  parietals  with  the  frontal." 

Next  in  frequency  to  the  coronal  are  the  mastoparietal  sutures,  and 
the  asterions,  the  points  of  divergence  of  the  former  from  the  lambdoid. 

Following  these  in  decreasing  succession  are  the  pterion,  thesquamo- 
parietal,  sagittal  and  masto-occipital  sutures,  the  orbits,  themetopic  and 
sphenofrontal  sutures,  the  bregma  and  obelion. 

Ninety-three  per  cent,  of  the  whole  number,  or  501.52  of  these  bones, 
are  situated  in  the  sutures  bordering  the  parietal  bones,  a  distribution 
quite  proportionate  to  the  greater  relative  extent  of  these  over  the 
remaining  sutures  of  the  membranous  cranium. 

Gruber  observed  their  presence  in  the  squamous  suture  on  one  or 
both  sides  in  5  per  cent,  of  4,000  skulls,  and  Humphrey  mentions  that  they 
may  here  be  two  or  three  rows  deep. 

In  the  skull  later  presented  by  the  writer,  the  whole  squamae  tem- 
porales  and  adjacent  portions  of  the  parietals  consist  of  numerous 
Wormian  bones,  completely  obliterating  this  suture,  and  rendering  sepa- 
rate distinction  of  asterion  and  pterion  ossicles  impossible. 

Although  they  are  very  rare  in  the  face,  and  between  the  sphenoid 
and  neighboring  bones,  according  to  Merkel  they  are  frequently  met 
along  the  orbital  margin,  and  Ward  has  observed  them  in  the  ethmo- 
sphenoidal  suture  and  in  the  lesser  wing  of  the  sphenoid. 

Hyrtl  records  one  in  the  internasal  suture,  and  one  in  the  crucial 
suture  of  the  palate.  Gegenbauer  mentions  their  occasional  occurrence 
at  many  points  in  the  articulation  of  the  bones  of  the  wall  of  the  nose  or 
the  maxillary  region. 

Mitchell  and  LeCount,  at  a  necropsy  on  a  case  of  acromegaly,  ob- 
served two  Wormian  bones  in  the  roof  of  the  right  orbit  and  four  in  the 
roof  of  the  left.  Their  numerous  occurrence  in  the  orbits  of  the  skull, 
previously  mentioned  by  the  writer  will  later  be  noted.  (Figs.  21,  22.) 

Metopic  Suture.  Simon  reports  numerous  Wormian  bones  through- 
out the  length  of  this  suture  in  the  skull  of  an  adult  male.  Chambellan 
reports  two  cases  of  Wormian  bones  in  this  suture,  and  Gruber  an  os 
interfrontal  at  the  site  of  the  bregma,  but  in  front  of  the  coronal  suture. 

Kobert  Harrison,  in  the  "Dublin  Dissector,"  says  that  "the  os  frontis 
may  develop  in  three  parts,  the  third  being  ovoid  and  situated  in  the 
median  line  separating  the  two  lateral  halves,  a  specimen  of  which  is  in 
the  museum." 


14 


CHARLES    A.    PARKER 


Intraparietal  Suture.  A  very  unusual  site  is  the  abnormal 
intraparietal  suture  in  divided  parietals.  Hrdlicka,  in  his  recent  exten- 
sive work  on  the  parietal  bone,  records  seven  cases,  collected  from  litera- 
ture, of  these  bones  situated  in  this  suture  in  man.  Five  were  on  the 
left  side,  and  two  on  the  right.  (Fig.  1.) 

Here,  also,  should  be  mentioned  the  isolated  observation  of  Gruber, 
who  found  in  the  petro-spheno-basilar  sutures  of  100  skulls,  119  extra 

bones  varying  in 
length  from  2  to  26 
mm.,  and  in  width 
from  1  to  9  mm., 
and  from  the  thin- 
ness of  paper  to  5 
mm.  thick.  They 
were  spongy  or  corn- 
pact  in  structure. 

The  frequency 
given  them  here 
would  place  them 
fourth  in  rank,  or 
next  to  the  masto- 
parietal  suture. 

Their  occurrence 
in  the  fontanelles 
has  been  noted  in 
the  following  order 
of  their  frequency: 
asterion,  pterion, 
lambda,  bregma,  and 
orbital  fontanelle. 


FIG.  1. — Wormian  bones  In  anomalous  parietal  su- 
ture. (After  Hrdlicka,  "Parietal  Bone  in  Man  and 
Other  Mammals,"  p.  258,  drawn  from  photograph  of 
Putnam's  first  case  of  parietal  division.) 


Os  Wormien  Asterique.  Chambellan  found  36  cases  in  110  skulls 
of  Parisians.  When  single  they  usually  range  in  diameter  from  4  to  8 
mm.,  but  they  may  be  found  measuring  but  1  or  2  mm. 

They  are  not  rarely  symmetrical  in  their  presence  on  the  two  sides, 
though  this  is  not  at  all  constant. 

Os  Wormien  Pterique.  The  same  author  observed  this  bone  but 
14  times  in  110  Parisians. 

These  bones  vary  in  size,  number  and  distribution,  similar  to  those 
at  the  asterion,  and  may  extend  variable  distances  along  the  upper  bor- 
der of  the  squama  temporalis  even  as  far  as  the  posterior  border. 
(Fig.  2.) 


WOBMIAN    BONES 


15 


Os  Wormien  Lamdatique.  This  bone  is  situated,  as  its  name  im- 
plies, in  the  posterior  fon- 
tanelle,  and  is  mentioned 
by  Worm  as  frequently 
assuming  a  triangular 
shape.  Hyrtl  says  it  was 
mentioned  by  Paracelsus, 
and  called  os  antiepilepti- 
cum  on  account  of  its 
supposed  relation  to  epi- 
lepsy. In  100  Bavarian 
skulls  Ranke  found  this 
bone  present  four  times. 

Os  Wormien  Bregmatique. 
This  bone    was    flrst    de- 
scribed by  Bertin,  and  is 
situated   in    the    anterior        FIG.  2.— Worm  ian  bones  In  the  squamous  suture. 
fontanelle.    In  the  skulls  of  198  Parisians  Chambellan  encountered  it  but 
twice.    In  one  case  it  was  oval,  and  in  the  other  quadrangular  in  form. 
They  were  single  and  of  nearly  equal  dimensions,  measuring  8  to  9  mm. 

in  width  by  2  cm.  in  length,  their 
long  axes  corresponding  in  direc- 
tion with  the  sagittal  suture. 
(Fig.  3.) 

Gruber,  in  a  series  of  contribu- 
tions to  Virchow's  Archives,  re- 
ports 70  cases  found  in  the  exami- 
nation of  11,928  skulls — an  average 
of  1  in  170.  One  of  these  measured 
5  cm.  by  6  cm.,  the  largest  he  had 
ever  seen.  In  two  instances  there 
were  three  bones,  one  being  the 
skull  of  a  hydrocephalic  boy;  and  in 
one  case  they  were  double. 

Quoting  Humphrey,  "Bertin 
Cruveilhier  and  Cuvier,  each  de- 
scribe the  os  bregmatique,  and 
Tiedemann,  in  the  Ztschr,  f  Phys. 
Ill,  gives  plates  of  two  in  this  sit- 
uation; also  Sandifort  in  his  "Mus. 
Anat."  Tab.  VIII.  There  are  sev- 
eral examples  in  the  museum  of 
Bonn.  Blandin,  "Anat."  I  describes 
Tiedemann  mentions  Stehelin 


FIG.  3.— Os  Wormien  bregmatique,  occu- 
pying the  anterior  fontanelle.  (After 
Cha  '  - 


lambellan.) 

them    in   each  of   the   fontanelles." 
Doveren,  Tarin  and  Sandifort  also  having  observed  bregmatic  bones. 


16 


CHARLES    A.    PARKER 


Os  Wormien  Orbitaire.  This  is  situated  at  the  junction  of  the  frontal, 
O9  planum  of  the  ethmoid  and  lesser  wing  of  the  sphenoid.  Chambellan 
had  not  seen  a  single  instance  in  the  nearly  five  hundred  skulls  he  had 
observed.  They  are  present  in  both  orbits  of  the  skull  presented  by  the 
writer,  along  with  numerous  others  in  the  neighboring  sutures.  (Figs. 
21  and  22.) 

Abnormal  Fontanelles.  In  the  abnormal  fontanelles,  Chambellan 
records  two  cases  of  os  Wormien  obelique  occurring  at  the  site  of  the 

obelion  in  the  skulls  of  198  Paris- 
ians. They  occurred  singly,  and 
were  somewhat  smaller  than  the 
ones  previously  described  at  the 
bregma,  their  long  diameters  ex- 
tending transversely  instead  of 
sagittally.  (Fig.  4.) 

Hamy  applies  to  the  same  bone 
the  name  os  sagittal,  but  os  obelique 
is  the  preferable  designation,  as  it 
refers  to  a  definite  place. 

In  the  descriptive  catalogue  of 
the  Warren  Museum  "a  Wormian 
bone  the  size  of  the  finger  nail  in 
the  middle  of  the  sagittal  suture, 
an  unusual  situation,  in  the  skull  of 
a  child  four  or  five  years  old"  may 
possibly  be  an  example  of  this  bone. 
M.  Pozzi  observed  one  instance 
of  os  Wormien  glabellaire  in  the  nasof  rontal  fontanelle  in  485  skulls;  but 
Chambellan  never  encountered  it  in  the  nearly  500  he  examined. 

In  this  class  are  included  the  fontanelle  bones  mentioned  by  Hrdlicka, 
referred  to  in  a  previous  chapter,  which  heretofore  have  been  considered 
sutural  rather  than  fontanelle  in  location.  Few  observers  have  at- 
tempted this  distinction,  and  occasionally  the  multiplicity  of  bones 
makes  the  differentiation  quite  impossible,  but  the  attempt  is  justified 
by  the  author  in  the  following  assertion:  "The  recognition  of  the  fon- 
tanel  bones  adds  considerably  to  our  proper  understanding  of  the 
subject  of  intercalated  bones  and  diminishes  very  much  the  numbers  of 
the  purely  accidental  of  these  ossicles." 

In  the  examination  of  45  complete  skulls  he  found  33  of  these  bones 
in  17,  the  majority  being  along  the  posterior  border  of  the  parietals  and 
usually  classed  as  lambdoidal.  In  105  calvaria,  upon  which  observations 
were  necessarily  limited  to  the  remaining  portions,  9  examples  were 
seen. 


FIG.  4.— Os  Wormien  obelique,  at  the  site 
of  the  abnormal  fontanelle  obelique. 
(After  Chambellan.) 


WORMIAN    BONES 


17 


DEVELOPMENT. 

Kolliker  describes  the  development  of  the  parietal  bone  as  follows: 
"In  the  region  of  the  parietal  bone  is  first  seen  a  number  of  small 
isolated  ossific  centres  which  become  more  numerous  and  blend  with  one 
another.  *  *  *  It  grows  partly  through  the  enlargement 
of  the  existing  osseous  framework,  and  partly  by  isolated  centres,  while 
at  the  same  time  the  interspaces  are  tilling  up  with  an  osseous  material, 
till  at  the  end  a  thin  com- 
pact bone  is  formed." 
(Fig.  5.)  What  is  here 
said  with  reference  to  the 
parietal  bone  may  be  ap- 
plied with  equal  truth  to 
the  other  membrane  bones 
of  the  cranium.  The  fur- 
ther development,  accord- 
ing to  Gegenbauer,  "is 
accomplished  b  y  small 
bony  crests  radiating 
toward  the  periphery.  Be- 
tween the  parts  already 
formed,  new  ones  appear, 
or  else  distinct  bony  pieces 
may  be  formed  outside  the 
growing  borders  of  the 
bones,  and  later  fuse  with 
the  principal  piece.  How- 
ever, this  fusion  of  isolated 
pieces  does  not  always 
occur,  and  it  sometimes 
happens  that  these  pieces 
remain  independent,  form- 
ing little  bony  fragments 


FIG.  5. — Embryonal  parietal  bones,  showing  two 
centres  of  ossification.    (After  Kanke.) 


in  the  dentations  of  the  sutures.  These  are  found  regularly  in  the  occipi- 
tal sutures.  When  they  are  found  at  an  advanced  stage  of  development 
these  little  bony  pieces  may  grow  without  joining  the  neighboring  bones. 
We  then  find  distinct  bones  in  the  sutures,  relatively  large,  and  articu- 
lating by  dentate  sutures  with  the  adjoining  bones.  These  are  the  so 
called  intercalary  or  Wormian  bones." 

The  origin  of  Wormian  bones  by  supernumerary  centres  or  by  division 
of  primary  centres  is  axiomatic,  since  they  must  either  arise  by  separate 


18 


CHARLES    A.    PARKER 


centres  and  remain  distinct,  or  develop  as  a  part  of  the  regular  centres 
and  in  some  manner  later  be  severed  from  their  origin.* 

A  later  development  of  occasional  small  Wormian  bones  is  mentioned 
by  Chambellan,  Sappey,  Porier  et  Charpey  and  others,  as  due  to  the 
gradual  compression  and  final  obliteration  of  the  pedicle  of  a  denticule  by 
its  adjacent  denticules.  This  is  but  another  method  of  origin  by  separa- 
tion from  a  primary  centre. 

Their  mode  of  growth  is  similar  to  that  of  the  larger  bones,  taking 
place  by  radiation  from  the  centre  to  the  periphery. 

Time  of  Appearance.  Beclard 
says  they  do  not  develop  till  five  or 
six  months  after  birth,  a  statement 
with  which  Humphrey  apparently 
agrees;  but  it  is  a  matter  of  common 
observation  that  they  are  not  in- 
frequent in  infants  at  birth.  Cham- 
bellan, in  the  skulls  of  ten  fetuses 
observed  six  in  the  lambdoid  suture, 
all  of  small  size.  In  the  crania  of 
fourteen  infants  under  twelve 
months,  and  one  child  of  two  years, 
he  observed  ten  instances,  occurring 
in  the  lambdoid  suture,  pterion,  as- 
terion  and  obelion.  In  the  Museum 
of  Obstetrics  and  Gynecology,  Hush 
Medical  College,  are  a  number  of 
fetal  skulls  showing  minute  osselets 
in  the  lambdoid  and  other  sutures.  The  skull  of  an  infant  in  the  first  post- 
natal months  shows  two  bones  occupying  the  site  of  the  parietal  foramina. 
One,  triangular,  measures  7  by  8  mm.  in  its  longest  diameters,  the  other, 
oblong,  4  by  7  mm.  (Fig.  6.) 

In  the  same  collection,  ISTo.  77,  is  the  skull  of  a  somewhat  older  in- 
fant, showing  the  large  Wormian  bones  occupying  the  right  half  of  the 
lambdoid  suture,  materially  changing  its  course,  and  developed  at  the 
expense  of  both  the  parietal  and  adjacent  occipital  bones.  The  larger 
bone  measures  4  by  5  cm.  and  the  smaller  2  by  3  cm.  They  are  not  the 
result  of  fracture.  The  posterior  fontanelle  is  inlaid  with  a  mosaic  of 
numerous  thin  flat  bones  from  1  to  2  mm.  wide,  and  5  to  10  mm.  long, 
arranged  in  quite  definite  vertical  lines.  (Fig.  7.) 

A  few  similar  shaped  ones  are  present  in  the  anterior  and  lateral 
fontanelles. 


FIG.  6. — Skull  of  an  infant,  showing  two 
Wormian  bones,  occupying  the  site  of  the 
parietal  foramina— fontanelle  obelique. 
(From  the  Gyn.  and  Obstet.  Mus.,  Bush 
Medical  College.) 


*See  Cruveilhier,   Rauber,    Humphrey,  Hyrtl,  Macalister,    Merkel.  Cunningham, 
Wistar,  Chambellan,  Rambaud  et  Renault,  Porier  et  Charpey,  Sappey. 


WOKMIAN    BONES 


19 


FIG.  7.— Skull  of  ;i  newborn  child  showing  largn  Wormian 
bones,  A  and  B,  in  the  right  lambdoid  region.  Many  smaller 
bones  are  also  present  in  the  posterior  fontanelle.  (From  the 
Gyn.  and  Obstet.  Museum  of  Rush  Medical  College,  No.  77.) 


This  striated  or  radiating  arrangement  is  mentioned  by  Humphrey 
as  having  been 
observed  by  him 
in  hydrocephalic 
skulls  where  they 
appeared  like  ex- 
tensions of  the 
radiations  of  the 
normal  bones, 
from  which,  how- 
ever, they  were 
quite  separate.* 

This  form  of 
growth  results 
from  the  linear 
arrangement  o  f 
separate  centres 
in  a  suture  ren- 
dering lateral 
development  un- 
necessary and  im- 
possible, permitting  only  extension  in  a  vertical  direction,  producing 
a  palisade  formation  across  the  gap  to  the  opposite  bone. 

Peckham,  in  the  "Reference 
Handbook  of  the  Medical  Sciences, " 
gives  a  cut  showing  two  Wormian 
bones  of  considerable  size  in  the 
posterior  fontanelle  of  a  newborn 
infant.  (Fig.  8.) 

In  some  cases  they  doubtless 
arise  synchronous  with  the  larger 
normal  centres,  as  for  instance, 
the  large  Wormian  bone  occupying 
such  a  considerable  portion  of  the 
frontal  region  of  the  skull  later  pre- 
sented in  this  article,  having  a 
greater  area  than  the  largest  piece 
in  the  parietal  region;  but,  just  as 
under  normal  conditions  some  cen- 
tres of  ossification  appear  later 

Fig.  8.— Skull  of  an  infant  whose  still-  than     nrhpr«     whpn     rhp    npppccitv 

birth  is  ascribed  to  the  influence  of  the  tnan    Otners— wnen    tne    necessity 

Wormian   bones  in  the  posterior  fonta-  arises  for  them— SO    it    is    probably 
nelle.    (Grace  Peckham  "Ref.  Handbook 

Med.  ScL,"  1894,  Art.  "Wormian  Bones.")      true   of    these   bones   that    their 


*Examples  of  this  are  referred  to  by  Humphrey  in  the  Museum  of  the  College  of 
Surgeons  No.  3842,  and  in  Sandifort's  "Mus.  Anat."  Tab.  VII.  Fig.  2. 


20  CHARLES    A.    PARKER 

period  of  origin  extends  over  considerable  intervals  of  time,  even  a  num- 
ber of  years,  in  some  instances. 

It  is  evident,  that  with  the  exception  of  the  few  small  ones  men- 
tioned as  occasionally  formed  by  inclusion  of  adenticule,  and  obliteration 
of  its  pedicle,  as  may  occur  almost  any  time  during  adult  life,  the  most 
of  these  bones  appear  during  the  earlier  years  of  cranial  development, 
while  the  fontanelles  are  open  and  the  bones  separable  at  the  sutures, 
as  the  only  time  when  they  may  be  of  service  or  can  obtain  room.  Cham- 
bellan  says  they  are  most  frequent  in  adults  in  those  skulls  with  open 
sutures,  becoming  fewer  as  the  sutures  are  obliterated.  Cruveilhier 
says  their  sutures  are  the  first  of  all  cranial  sutures  to  be  effaced.  This 
is  more  particularly  true  for  those  of  smaller  dimensions  than  for  the 
larger  ones  which  seldom  disappear  entirely,  though  they  may  be  par- 
tially united  to  the  neighboring  bones.  Their  diminution  in  number 
with  the  obliteration  of  the  sutures  is  the  natural  consequence  of  the 
disappearance  of  the  conditions — sutures — which  originally  distinguished 
them  from  the  adjacent  bones,  causing  them  eventually  to  become 
integral  parts  of  the  latter. 

FUNCTION. 

With  reference  to  their  function  Cruveilhier  says: 

"They  are  looked  upon  as  supplementary  points  of  ossification,  and 
not  as  playing  an  important  role  in  the  mechanism  of  the  solidity  of  the 
cranium,  as  would  be  supposed  from  the  name,  'Keys  of  the  vault,' or 
'Clefts  de  route,'  given  them  by  some  anatomists."  Ward  expresses  simi- 
lar views,  though  he  quotes  Bichat  as  saying  they  are  designed  to 
strengthen  the  cranium.  According  to  Humphrey;  "They  are  evidently 
stop-gaps  developed  in  the  membranous  covering  of  the  brain  when  the 
extension  of  the  regular  osseous  nuclei  is  likely  for  some  reason  to  be 
insufficient  to  cover  the  cranial  cavity."  Wistar  says  practically  the 
same,  and  Manouvrier,  "They  are  due  to  an  insufficiency  of  the  normal 
centres." 

MORPHOLOGY. 

As  to  their  morphological  value  they  are  not  reversional  types  as  a 
rule,  the  more  numerous  bones  of  the  skulls  of  other  animals  having 
their  representatives  in  the  separate  ossific  centres  from  which  the 
larger  bones  of  the  human  cranium  are  regularly  formed,  and  not  in  the 
occasional  Wormian  bones.  (Humphrey,  Manouvrier.)  According  to 
Macalister,  "They  are  a  testimony  of  the  low  morphological  value  of 
centres  of  ossification  in  membrane  bones."  Merkel  says,  "For  the  most 
part  they  are  the  product  of  a  development  with  too  little  energy." 


WOKMIAN    BONES  21 

Yet,  at  times  division  of  the  parietals  or  irregular  development  of  the 
occipital  and  other  bones  may  present  features  of  considerable  morpho- 
logical interest,  often  making  it  difficult  or  impossible  to  distinguish 
between  those  bones  developed  separately  from  normal  centres,  and 
those  arising  from  true  supernumerary  ossific  areas.  The  peculiar  man- 
ner of  development  of  the  squama  occipitalis  affords  opportunity  for  a 
great  variety  of  examples  of  irregular  development  with  consequent  con- 
fusion of  morphological  relations.  The  lower  part  of  the  squama  occipi- 
talis, including  the  inion,  is  developed  in  cartilage,  while  the  remaining 
upper  portion  is  developed  in  membrane.  As  formerly  taught  by  Broca, 
1875,  and  most  other  anatomists,  the  entire  squamous  portion  is  devel- 
oped by  four  centres  of  ossification  placed  in  two  superimposed  symmet- 
rical pairs,  the  upper  in  membrane  and  the  lower  in  cartilage.  The 
adjacent  portions  of  each  pair  fuse,  and  then  the  upper  part  unites  with 
the  lower,  beginning  at  the  inion,  leaving  at  first  vertical  and  horizontal 
incisures  at  the  margins. 

The  horizontal  incisures  are  frequently  present  at  birth.  Failure  of 
union  of  the  upper  portion  with  the  lower  results  in  the  formation  of 
the  socalled  interparietal  bone,  the  analogue  of  a  separate  bone  of  that 
name  constant  in  many  of  the  mammalia.  This  bone  is  developed  from 
normal  centres,  and  is  therefore  not  a  true  Wormian  bone. 

Since  then  Merkel  and  Kolliker,  1879,  and  Hagen  and  Anoutchine, 
1879  and  1880,  have  described  eight  centres  of  ossification  instead  of  four 
for  the  squama  occipitalis;  the  first  two  authors  arranging  them  four  on 
a  side,  one  above  the  other,  the  last  two  arranging  them  three  on  a 
side,  one  above  the  other,  with  the  fourth  placed  lateral  to  the  third, 
or  uppermost  one,  which  makes  the  summit  of  the  bone.  In  1881  Hann- 
over of  Copenhagen,  reduced  the  number  to  two,  one  for  the  membranous 
portion  and  one  for  the  cartilaginous  portion,  thus  reverting  to  the  views 
of  Sappey  in  1867.  Debierre  in  1895  gave  six  centres  of  ossification  for  the 
squama  occipitalis.  (Porier  et  Charpey.) 

Wiedersheim  in  the  same  year,  in  his  "Structure  of  Man,"  gives  the 
same  number  of  centres,  and  arranged  in  a  similar  order  as  follows: 
supraoccipital,  from  the  cartilaginous  portion,  interparietal  and  pre- 
interparietal,  the  latter  according  to  the  author,  being  constant  as  a 
separate  bone  only  in  the  horse. 

According  to  Debierre  its  occurrence  in  man  constitutes  the  os 
epactal. 


22 


CHARLES    A.    PARKER 


The  accompanying  diagrams  from  Wiedersheim's  work,  show  very 
clearly  this  morphology.    (Fig.  9.) 

A  B 


FIG.  9.— Development  of  the  occipital  bone.  (After  Dr.  K.  Wiedersheim,  "The 
Structure  of  Man."  1895,  p.  56.)  A  Development  of  the  squama  occipitalis  by  six  cen- 
tres. 8  O.  supraoccipital;  I  p,  interparietal ;  i  PP.  pre-interparietal;  B  o.  basioccipital; 
E  O,  exoccipital.  B  Later  stage  of  development.  C  Interparietal  bone  formed  from 
the  upper  four  centres.  D  Pre-lnterparietal  bones  formed  from  the  upper  pair  of 
nuclei.  These  remain  normally  separate  only  in  the  horse.  (Wiedersheim  designates 
these_  latter  as  interparietals,  though  the  view  expressed  here  appears  to  be  the  proper 
one,  judging  from  the  plan  of  development.) 


WORMIAN      BONES 


23 


Figures  10,  11  and  12  are  instances  of  irregular  development  of  this 
region.    (For  Fig.  12  see  page  24.) 


FIG.  10.— Wormian  bones  in  the  lamb- 
doid  suture.  (From  the  Anatomical  Labo- 
ratory of  Rush  Medical  College.) 


FIG.  11.— Quadrangular  bone  occupying 
the  apex  and  adjacent  portion  of  the 
squama  occipitalis,  apparently  represent- 
ing the  enlarged  and  ununited  pre-inter- 
parietal  portion.  (From  the  Anatomical 
Laboratory  of  Rush  Medical  College.) 


With  this  evident  confusion  as  to  the  exact  number  and  arrangement 
of  the  centres  in  this  region  of  the  skull,  further  "testimony  of  the  low 
morphological  value  of  centres  of  ossification  in  membrane  bones,"  the 
frequent  impossibility  of  accurate  distinction  between  true  and  false 
Wormian  bones  is  manifestly  apparent.  Still,  certain  special  terms  are 
applied  to  more  or  less  regular  formations  commonly  observed  here. 
They  are  the  os  interparietal,  os  epactal  and  os  Inca. 

IXTERPARIETAL   BONE. 

By  many  authors  these  terms  are  synonymous  and  cover  a  consider- 
able range  of  variation  from  all  of  the  membranous  portion  of  the  squama 
occipitalis  to  a  small  os  lambdatique.  The  following  description  by 
Broca  probably  best  represents  this  special  formation,  including  as  it 
does  all  of  the  membranous  portion  of  the  occipital  bone,  the  line  of  the 
adventitious  suture,  the  interparietal,  corresponding  exactly  with  the 
lower  posterior  limit  of  the  development  of  Wormian  bones  in  the  skull 
later  described  in  this  article. 

"L'  interparidtal  se  distingue  par  la  position  de  sa  suture  qui  aboutit 
de  chaque  cote"  a  la  partie  inferieure  de  la  suture  lamdoide  et  qui,  sur  la 
ligne  mediane  passe  a  peine  a  un  centimetre  et  demi  au  dessus  de  1'Inion. " 


24 


CHARLES    A.    PARKER 


r, 


FIG.  12 — Peculiar  development  of  the  occipital  bone  observed  in  two  skulls  in  the 
Osteological  Collection  at  the  University  of  Chicago.  In  A  the  two  symmetrical  lateral 
areas  apparently  represent  a  divided  interparietal  separated  by  the  sagittal  suture 
above,  and  by  a  tongue  of  bone  extending  from  below.  In  B  the  separation  is  more 
complete,  the  tongue  of  bone  entirely  separating  the  two  portions.  In  both  cases  the 
"interparietal"  suture  is  present  the  greater  part  of  the  distance  from  the  mastoid 
process  to  the  inion. 

Os  INCA. 

Eivero  and  Tschudi  in  their  "Peruvian  Antiquities"  described  abone 
later  designated  under  this  name.  As  much  confusion  exists  as  to  its 
morphological  position  the  following  quotation  from  these  authors  is 
here  introduced: 

"In  conclusion  it  may  be  proper  to  notice  an  osteologic  anomaly,  very 
interesting,  which  is  observed  in  the  crania  of  all  the  three  races  (Chin- 
cas,  Aymares,  Huancas)  and  it  is  this;  that  those  children  of  tender 
years,  in  the  first  months  after  birth,  present  an  interparietal  bone  (os 
interparietal)  perfectly  distinct:  a  bone  which,  as  its  name  indicates,  will 
be  found  placed  between  the  two  parietals,  and  having  a  form  more  or 
less  triangular,  whose  sharpest  angle  is  above,  and  is  bounded  by  the 
posterior  edges  of  the  parietal  bones,  while  its  base  attaches  itself  to  the 
occipital  bone  by  a  suture  which  runs  from  the  angle  of  union  of  the  tem- 
poral with  the  occipital  bone,  a  little  above  the  semi-circular  line,  to  the 
similar  angle  on  the  opposite  side.  It  follows  that  this  interparietal 
bone  occupies  precisely  that  part  of  the  occiput  which  in  the  other  crania 
is  occupied  by  the  upper  portion  of  the  occipital,  and  which  is  connected 
with  the  parietals  by  the  lambdoid  suture.  At  four  or  five  months  this 
bone  is  regularly  united  to  the  occipital.  It  is  a  circumstance  worthy  of 
attention  of  learned  anthropologists,  that  there  is  thus  found  in  one 
section  of  the  human  race  a  perpetual  anomalous  phenomenon,  which  is 


WOKMIAN    BONES 


wanting  in  all  others,  but  which  is  characteristic  of  the  ruminant  and 
carnivorous  animals." 

The  exposition  of  the  fallacy  of  this  premature  conclusion,  by  Jac- 
quart.  lias  already  been  mentioned.  Gosse  came  to  similar  conclusions 
regarding  their  morphological  significance,  although  he  believed  they 
more  frequently  remained  separate  in  the  Peruvians. 

This  accurate  description,  together  with  the  accompanying  figure 

(Fig.  13.),  from  the  same  source,  leave 
absolutely  no  room  for  doubt  as  to  its 
morphology,  that  it  represented  the 
generally  recognized  interparietal 
bone  of  today  developed  from  the  en- 
tire membranous  portion  of  the 
squama  occipitalis. 

Os  EPACTAL. 

Broca  makes  no  distinction  between 
the  os  epactal  and  the  os  Inca,  which 
he  describes  as  follows: 

'•L'os  des  Incas  est  un  os  Wormien, 
triangulaire,  qui  est  vraiment  surnu- 
meraire,  qui  est  symetrique  de  grande 
dimension  et  qui  occupe  le  lambda." 
Chambellan  also  considers  the  two 
terms  synonymous,  and  asserts  that  it 
maybe  single  or  double,  or  even  divided  in  three  parts.  According  to 
these  authors  it  is  not  an  interparietal,  which  is  a  false  Wormian  bone. 
These  conclusions  must  be  based  on  entirely  erroneous  conceptions  of  the 
os  Inca  as  just  described,  and  detract  from  the  force  of  their  opinions 
with  regard  to  the  os  epactal. 

Topinard,  Jacquart,  Kambaud  et  Benault,  Milne  Edwards,  Testut, 
Porier  et  Charpey,  Cunningham  and  many  other  writers  use  the  word 
interparietal  and  epactal  as  synonymous  terms  designating  varying  pro- 
portions of  the  squama  occipitalis,  making  no  endeavor  to  apply  them 
separately  to  different  formations;  thus  probably  best  avoiding  the  con- 
fusion naturally  arising  from  too  much  specialization  in  a  region  nor- 
mally of  such  doubtful  morphology. 

The  writer  believes  that  the  term  interparietal,  in  its  true  sense, 
should  be  applied  only  to  the  bone  developing  from  the  whole  mem- 
branous portion  of  the  squama  occipitalis,  the  lower  boundary  of  which 
has  already  been  described  by  Broca,  as  a  suture  converging  from  either 
side  at  the  lower  part  of  the  lambdoid  to  pass  in  the  median  line  scarcely 
one  and  one-half  centimetres  above  the  inion. 

As  it  is  evident  that  the  terms  os  Inca  and  os  epactal,  as  they  are 
generally  used,  are  rather  suggestive  of  authority  than  of  morphology, 
further  consideration  of  them  need  not  be  given. 


FIG.  13.— Skull  of  a,  youth  of  the 
Chincas,  10  to  12  years  old,  in  which  the 
"occipital"  suture  may  be  seen  open 
throughout  its  whole  length.  (From 
"Peruvian  Antiquities."  p.  38.) 


26  CHARLES    A.    PARKER 


ANTHROPOLOGICAL    SIGNIFICANCE. 

Especially  interesting  from  the  anthropological  standpoint  is  the 
significant  relation  between  the  number  of  Wormian  bones  and  the 
cubage  of  the  skulls  selected  for  study.  This  is  shown  in  the  following 
tables  from  Chambellan,  the  number  of  bones  being  on  a  basis  of  100 
skulls  for  each  group. 

No.  or  SKULLS  TOTAL  NUMBER  OF 

OBSERVED.  NAME  OF  GROUP.  WORMIAN  BONES. 

MALES 

56 Auvergnats 626 

124 Parisians .587 

46 Neo-Caledonians 519 

89 Negroes 501 

44 Incas 481 

FEMALES 

17 Auvergnats 600 

56 Parisians 551 

6 Neo-Caledoriians 455 

11 Negroes 427 

6  Incas 493 

CUBAGE  OF  MALE  SKULLS. 
No.  OF  SKULLS 

OBSERVED.  NAME  OF  GROUP.  CAPACITY. 

44  Auvergnats 1,535  cc. 

40 Parisians 1,511  cc. 

38 Neo-Caledonians 1,471  cc. 

38 Negroes 1,410  cc. 

37 Incas 1,324  cc. 

The  Auvergnats  have  the  most  Wormian  bones,  626  to  100  skulls,  the 
Parisians,  Neo-Caledonians  and  Negroes  following  in  order  of  decrease  to 
the  Incas  with  but  481. 

Comparing  these  numbers  with  the  cubage  of  the  corresponding 
skulls  a  similar  regular  decrease  in  capacity  is  shown  from  the  Auver- 
gnats to  the  Incas,  thus  establishing  the  general  conclusion  that  the 
number  of  Wormian  bones  is  greatest  in  the  skulls  of  the  largest  capacity, 
and  correspondingly  diminishes  as  the  cubage  decreases.  See  the  follow- 
ing table: 

Auvergnats 626  Wormian  bones.    Capacity,  1,535  cc. 

Parisians 587  "  "  "         1,511  cc. 

Neo-Caledonians 519  "  "  "         1,471  cc. 

Negroes 501  "  "  "         1,410  cc. 

Incas 481  "  "  "         1,324  cc. 


WORMIAN    BONES  27 

The  cubage  of  the  female  skulls  was  neglected,  yet  a  diminished  total 
in  each  of  the  groups  except  the  last,  probably  accounted  for  by  the  small 
number  of  skulls  (six)  observed,  shows  here  also  the  same  definite  corre- 
spondence between  the  numbers  and  the  well  known  smaller  capacity  of 
these  skulls. 

Analagous  and  equally  interesting  results  corroborative  of  this 
relation  are  obtained  by  examination  of  the  data  relating  to  the  other 
groups  of  skulls  examined  by  this  writer. 

Hydrocephales,  adults.  13    1092  Wormian  bones.    Capacity 3,727  cc. 

Hemi-microcephales  . .  .15      366  "  "  "  less  than  1,100  cc. 

Apes,  anthropoid 52       96  "  "  "   in  gorilla   531  cc. 

Microcephales 5       40  "  "  "  433  cc. 

Apes,  non-anthropoid.  .73        17  "  "  "much    less    than 

microcephales. 

The  commonly  observed  increase  of  these  bones  in  hydrocephalic 
skulls  is  here  very  apparent. 

Comparing  these  with  the  skulls  of  the  Auvergnats,  the  largest  nor- 
mal skulls  studied,  the  relation  of  number  to  capacity  is  very  strikingly 
shown. 

Auvergnats 600  Wormian  bones Capacity,  1,535  cc. 

Hydrocephales 1,092         "  "      "        3,727  cc. 

Equally  noticeable  is  the  diminished  number  in  the  crania  of  small 
cubage  as  the  anthropoid  apes  and  microcephales. 

Chambellan  also  studied  their  occurrence  in  brachycephalic  and 
dolichocephalic  skulls,  examining  fifty  of  the  former  and  twenty-five  of 
the  latter,  with  the  result  of  finding  the  equivalent  of  676  Wormian  bones 
to  the  hundred  skulls  in  the  former,  and  362  in  the  latter. 

A  comparison  of  the  cubage  of  some  of  these  skulls  gave  the  follow- 
ing results: 
No.  OF  SKULLS.  TOTAL  CAPACITY.  AVERAGE. 

Brachycephales,  12 18,311  cc 1,525  cc. 

Dolichocephales,  28 42,145  cc 1,505  cc. 

The  number  of  skulls  is  too  small  to  furnish  the  most  desirable  proof, 
but  from  all  that  has  been  shown  the  evidence  is  very  conclusive  that  in 
spite  of  numerous  isolated  exceptions,  the  general  rule  for  groups  holds 
good,  that  the  number  of  Wormian  bones  increases  with  the  capacity  of  the 
skull,  regardless  of  the  cause  of  the  enlargement. 

Finally  their  occurrence  on  the  two  sides  of  the  head  was  separately 
recorded  with  the  following  results: 

Parisians Right  side  281 Left  side  255 

Auvergnats "        "    307 "      "    288 

Neo-Caledonians "        "    299 "      "    197 

Negroes "        "    295 , "      "    215 

Incas..  "        "    257..  "      "    230 


28  CHARLES    A.    PARKER 

Showing  their  greater  frequency  on  the  right  side  in  all  the  groups 
examined. 

SUTURAL,  LENGTHS. — With  the  object  of  establishing  a  probable 
direct  relation  between  the  increase  in  Wormian  bones,  and  the  general 
increase  in  sutural  length,  and  between  their  preponderence  on  the  right 
side  and  a  greater  corresponding  dextral  sutural  length,  careful  measure- 
ments were  made  by  the  writer  upon  50  normal  skulls  to  obtain  data 
upon  which  conclusions  might  be  based.  Measurements  were  made  of 
the  coronal,  lambdoid,  squamous,  (including  the  sphenoparietal  and 
mastoparietal),  and  sagittal  sutures,  as  they  comprised  most  of  the 
sutures  bearing  Wormian  bones.  In  the  first  three,  including  the  two 
transverse  sutures,  the  two  sides  were  recorded  separately.  The  cephalic 
index  was  also  taken  in  each  case,  and  the  skulls  divided  into  dolicho- 
cephalic, mesaticephalic  and  brachycephalic  classes.  The  average  total 
sutural  length  in  22  dolichocephalic  skulls  was  78.  cm.,  in  16  mesati- 
cephalic skulls  78.7  cm.,  and  in  12  brachycephalic  skulls  79.8  cm.,  or 
including  the  last  two  in  one  group,  in  28  brachycephalic  skulls  79.2  cm. 
Chambellan  determined  that  the  brachycephales  have  a  greater  cranial 
capacity  than  the  dolichocephales— he  did  not  distinguish  a  middle  class 
— and  that  they  also  have  a  larger  number  of  Wormian  bones  correspond- 
ing to  their  increase  in  cubage,  agreeing  with  his  previously  mentioned 
law  that  as  a  class  the  larger  the  cranial  capacity  the  greater  the  number 
of  Wormian  bones.  A  comparison  of  his  results  with  those  obtained 
from  the  foregoing  sutural  measurements  suggests  certain  fundamental 
relations;  first,  as  the  brachycephalic  skulls  have  a  greater  number  of 
Wormian  bones  and  also  a  greater  sutural  length,  that  the  greater  the 
sutural  length  of  a  skull  the  greater  the  number  of  Wormian  bones;  and,  second, 
as  the  brachycephalic  skulls  have  a  greater  cranial  capacity  with  a 
greater  sutural  length,  that  the  larger  the  cranial  capacity  of  a  skull,  the 
greater  its  sutural  length.  In  other  words,  in  man  at  least,  the  number  of 
Wormian  bones  and  the  capacity  of  a  skull  bear  a  direct  relation  to  the 
length  of  its  sutures. 

These  relations  thus  established  by  tangible  data  are  such  as  we 
would  a  priori  expect  to  obtain,  since  the  Wormian  bones  develop  in  the 
sutures  and  the  longer  the  suture  the  greater  the  opportunity  for  increase 
in  their  numbers,  and  the  greater  the  cranial  capacity  the  longer  the 
sutures  necessary  to  unite  the  enlarged  parts.  In  the  first  principle 
also  is  to  be  found  the  explanation  of  their  greater  frequency  on  the 
right  side,  as  the  total  sutural  length  of  the  right  side  of  the  50  skulls 
was  1,666.2  cm.,  as  compared  with  a  total  of  1,643.5  cm.,  on  the  left,  the 
excess  being  limited  to  the  squamous  and  coronal  sutures.  Although  of 
secondary  importance  to  the  main  subject,  certain  interesting  observa- 
tions appear  in  the  comparison  of  the  coronal  and  lambdoid  sutures  in 
the  two  general  classes  of  skulls.  In  the  22  dolichocephales  the  coronal 


WORMIAN    BONES  29 

sutural  length  averaged  22.7  cm.,  and  in  28  brachycephales  23.4  cm., 
while  the  lambdoid  in  22  dolichocephales  averaged  19.5  cm.,  and  in  28 
brachycephales  19.3  cm.,  showing  a  very  definite  increase  in  sutural 
length,  associated  with  a  corresponding  increased  cranial  capacity,  in 
the  anterior  and  lateral  regions  of  the  brachycephalic  skulls  with  a 
stationary  or  slightly  diminished  capacity  in  the  posterior  region  of  the 
same  skulls.  The  lateral  increase  is  particularly  emphasized  by  similar 
comparisons  of  the  squamous  sutures  in  the  three  classes  of  skulls,  as  the 
average  length  in  22  dolichocephales  was  23.2  cm.,  in  16  mesaticephales 
23.5  cm.,  and  in  12  brachycephales  24.9  cm.,  a  progressive  increase  from 
the  first  to  the  last.  At  the  same  time  the  sagittal  suture  is  shortened 
from  an  average  of  12.6  cm.,  in  dolichocephales  to  an  average  of  12.4  in 
brachycephales.  The  direct  relation  of  the  increase  in  size  in  this 
region — the  temporal  fossa — to  brachycephaly,  with  special  reference  to 
the  causative  factor  of  the  jaws  in  its  production,  is  admirably  demon- 
strated in  an  exceedingly  interesting  scientific  paper  by  Arthur  Thom- 
son, presented  before  the  recent  International  Medical  Congress,  at 
Madrid. 

CAUSES. 

The  larger  number  of  Wormian  bones  doubtless  arises  from  local 
metabolic  variations  entirely  physiological  and  compensatory  in  charac- 
ter. Their  innocuous  occurrence  in  practically  all  normally  developed 
skulls  is  opposed  to  an  essentially  pathological  origin,  and  only  when 
presenting  particularly  abnormal  features  should  it  come  into  considera- 
tion. Their  occasional  association  with  definite  pathological  processes 
may  be  secondary  or  incidental,  and  rarely  a  direct  or  specific  result  of 
the  primary  affection.  Pathological  or  physiological  variations  can 
directly  produce  Wormian  bones  in  but  two  ways;  either  by  permanently 
segregating  offshoots  from  pre-existing  centres,  or  by  causing  an  excess 
of  original  centres  themselves.  As  the  distinction  between  physiological 
and  the  milder  pathological  fetal  nutritional  variations  is  frequently 
so  obscure  the  difficulty  of  positively  ascribing  these  effects  on  osteogene- 
sis  to  definite  pathological  causes  is  plainly  apparent.  A  physiological 
excess  of  primary  ossific  nuclei,  possibly  sometimes  hereditary  or  atavistic 
is  well  known  to  occur,  and  it  is  possible  that  some  of  the  definite  patho- 
logical processes,  or  the  more  subtle  so  called  degenerative  influences 
may  also  occasionally  produce  similar  results;  but  there  is  no  doubt  that 
most  of  the  Wormian  bones  properly  ascribed  to  specific  pathological 
processes  directly  affecting  osteogenesis  are  produced  by  the  permanent 
segregation  of  nuclei  from  pre-existing  centres. 

Rachitis,  scrofula,  violent  pressure,  heredity,  syphilis,  and  in  addi- 
tion, in  the  writer's  case,  osteogenesis  imperfecta,  chondrodystrophia 
fetalis,  and  cretinism,  have  all  been  considered  in  the  pathology  of  their 


30  CHARLES    A.    PARKER 

development.  Lombroso  and  Ferrero  assert  their  increased  frequency  in 
the  crania  of  criminals.  Of  the  pathological  conditions  in  which  the 
occurrence  of  Wormian  bones  is  but  incidental  or  secondary  to  the  pri- 
mary affection,  hydrocephalus  is  probably  the  best  known.  Other  affec- 
tions gradually  producing  great  cranial  enlargement  would  probably  lead 
to  equally  excessive  development  of  these  bones. 

Their  production  by  pressure  is  evidenced  by  their  increased  fre- 
quency in  the  coronal  suture  in  the  skulls  of  the  flat  head  or  similarly 
deformed  Indians  reported  by  Dorsey,  and  those  referred  to  by  the  author 
in  a  previous  paragraph.  Whether  flattened  by  direct  pressure  on  the 
occiput  and  forehead,  or  by  compressing  bands  around  the  back  of  the 
head,  the  compensatory  lateral  enlargement  is  especially  effective  in  the 
coronal  region,  correspondingly  increasing  its  predilection  for  Wormian 
bones.  Their  occurrence  is  secondary  to  the  sutural  diastasis. 

The  role  of  heredity  in  their  production  without  the  relative  occur- 
rence of  pathological  features  is  distinctly  physiological. 

Their  association  with  stigmata  of  degeneration,  tuberculosis,  syphi- 
lis and  similar  dycrasiae  must  be  considered  quite  incidental  to  the  pri- 
mary affection,  and  only  possessing  a  possible  aetiological  relation  when 
presenting  distinctly  unusual  or  abnormal  local  features. 

Chondrodystrophia  fetalis  and  osteogenesis  imperfecta  are  prenatal 
in  origin,  rachitis  and  cretinism  are  essentially  postnatal  affections, 
though  possibly  occasionally  occurring  earlier  under  the  influence  of 
maternal  dycrasiae  similar  to  their  own  specific  pathologies.  Except  in 
the  latter  extremely  rare  instances,  the  influences  of  these  two  chrono- 
logical classes  of  affections  on  osteogenesis  must  differ  considerably  in 
their  opportunities,  if  not  in  their  effects;  the  prenatal  affections  alone 
being  capable  of  profound  fundamental  disturbances  of  osteogenesis,  the 
postnatal  diseases  being  limited  in  the  production  of  separate  nuclei  to 
their  action  on  the  margins  of  the  bones  only. 

Osteogenesis  in  cretinism  exhibits  a  similar  characteristic  sluggish- 
ness or  inhibition  in  its  course  to  that  observed  in  the  growth  of  other 
tissues  in  this  disease,  a  condition  apparently  most  unfavorable  to  the 
development  of  supernumerary  ossiflc  nuclei;  although  in  the  single  case 
mentioned  by  Hyrtl  the  extraordinary  number  of  300  was  found  in  the 
lambdoid  suture  of  a  cretin. 

On  the  other  hand,  however,  the  notably  irregular  osteogenesis  of 
rachitis  would  appear  to  specially  favor  the  separation  of  such  nuclei 
from  pre-existing  centres,  and  this  disease  is  particularly  mentioned  by 
Gosse  as  one  of  the  causes  of  Wormian  bones.  Yet  its  postnatal  occur- 
rence and  usually  short  duration  necessarily  reduce  its  direct  aetiological 
relation  to  narrow  chronological  and  mensural  limits. 

Chondrodystrophia  fetalis  is  a  fundamental  disease  of  chondrogenesis, 
secondarily  affecting  only  bones  of  chondral  origin  so  that  while  the  base 


WORMIAN    BONES  31 

of  the  skull  may  present  gross  deformities  the  membrane  bones  show  no 
specific  alterations.  It  thus  bears  no  aetiological  relation  to  Wormian 
bones. 

Osteogenesis  cranii  imperfecta,  or  aplasia  cranii,  with  its  irregular 
development  of  isolated  patches  of  bony  tissue,  appears  to  be  the  best 
known  pathological  condition  to  favor  excessive  development  of  these 
bones.  A  beautiful  specimen  of  this  condition  is  the  fetal  skull  described 
by  Vrolik  in  a  later  paragraph.  (Fig.  23.) 

Back  of  these  fetal  dystrophias  commonly  lie  parental,  usually  ma- 
ternal, dyscrasiae,  and,  in  the  Vrolik  case  syphilis  apparently  played  an 
important  part.  In  the  writer's  case  Prof.  Hektoen,  in  a  separate  article 
more  especially  concerning  the  general  dystrophy,  considers  rachitis, 
cretinism,  chondrodystrophia  fetalis  and  osteogenesis  imperfecta  as 
possible  causes  of  the  various  body  changes.  As  neither  the  changes  in 
the  skull  nor  in  the  body  conform  to  those  of  rachitis  or  cretinism,  they 
were  excluded  as  aetiological  factors,  and  the  preference  given  to  osteo- 
genesis imperfecta  and  chondrodystrophia  fetalis.  The  body  changes 
with  the  short  and  misshapen  limbs  correspond  closely  with  those  ob- 
served in  the  latter  disease,  and  differ  from  those  of  the  former  in  the 
apparent  absence  of  multiple  fractures.  On  the  other  hand,  the  changes 
in  the  cranium  correspond  to  those  of  osteogenesis  imperfecta,  while  the 
base  of  the  skull  presents  none  of  the  lesions  of  chondrodystrophia 
fetalis. 

The  successive  occurrence  of  the  two  diseases  is  doubtless  possible, 
but  the  restriction  of  the  two  processes  to  separate  and  distinct  areas 
instead  of  each  acting  generally,  develops  an  apparently  unique  variation 
from  the  usual  types.  Considering  the  analogy  between  this  skull  and 
the  one  described  by  Vrolik,  its  excessive  number  of  Wormian  bones  can 
best  be  ascribed  to  the  changes  occurring  in  osteogenesis  imperfecta.  On 
account  of  the  incomplete  history  it  is  impossible  to  determine  any 
parentalldyscrasiae. 

The  changes  in  the  face  of  this  skull,  of  a  distinctly  degenerative 
character,  are  in  all  probability  due  to  the  same  general  dyscrasia 
variously  affecting  the^different  regions  of  the  body. 


32  CHARLES    A.    PARKER 


MEDICAL    ASPECTS. 

Their  specific  medical  importance  is  exceedingly  limited.  By  simu- 
lating normal  sutures  or  fractures,  the  occurrence  of  adventitious  sutures 
may  occasion  confusion  in  examination  of  the  skull. 

Nicolas  Saucerotte,  in  his  "Melanges  De  Chirurgie,"  mentions  the 
case  of  a  clergyman  who  was  thrown  from  his  horse  and  suffered  an 
injury  in  the  occipital  region.  The  first  attendant  on  examining  the 
wound,  pronounced  it  a  fracture  of  the  skull,  and  suggested  trephining 
as  the  proper  treatment.  Dr.  Nouvelle,  a  clever  surgeon  of  the  time, 
was  called  in  consultation,  and  opposed  the  diagnosis  of  fracture.  He 
contended  that  the  apparent  line  of  fracture  was  the  adventitious  suture 
of  a  Wormian  bone.  The  skull  was  not  trephined.  Upon  his  recovery 
the  grateful  clergyman  promised,  should  he  die  first,  that  the  doctor 
whose  knowledge  and  skill  had  saved  his  skull  intact  while  he  lived 
should  have  the  opportunity  of  examining  it  after  his  death.  Some 
years  later  he  died,  and  the  doctor  found  at  the  site  of  the  injury  a  tri- 
angular shaped  Wormian  bone  measuring  one  inch  and  ten  lines  in  its 
greatest  diameter,  by  one  inch  and  a  half  in  its  lesser,  occupying  the 
upper  angle  of  the  occipital  bone,  its  transverse  suture  having  previously 
been  mistaken  for  a  fracture  of  the.  skull.  This  is  the  only  instance  I 
have  found  recorded  of  a  Wormian  bone  becoming  of  surgical  importance, 
although  it  is  highly  probable  that  such  confusion  has  not  been  so  rare 
as  this  single  record  would  indicate. 

In  the  "New  York  Medical  Record"  for  1888,  Grace  Peckham  reports 
three  cases  occurring  during  her  internship  in  the  New  York  Hospital 
for  Women  and  Children,  in  which  Wormian  bones  in  the  posterior  fonta- 
nelle  gave  rise  to  confusion  in  the  examination  of  the  presenting  head, 
and  were  considered  responsible  for  the  death  of  all  three  children,  as 
no  instruments  were  used  in  the  deliveries.  These  are  the  only  recorded 
instances  in  which  pathological  influences  are  ascribed  to  these  bones. 


AUTHOR'S  CASE  OF  EXTRAORDINARY  DEVELOPMENT  OF 
WORMIAN  BONES.* 


This  interesting  skull  was  obtained  by  Prof.  Hektoen  at  an  autopsy 
on  a  white  man  about  45  years  of  age.  The  man  had  been  a  resident  of 
Chicago,  and  possessed  only  a  fair  degree  of  intelligence.  He  had  always 
been  a  cripple,  the  most  noticeable  deformities  being  a  marked  dorso- 
lumbar  kyphosis  and  very  imperfectly  developed  and  misshapen  limbs. 

The  special  body  changes  have  been  described  by  Prof.  Hektoen  in  a 
separate  article,  t 

The  skull  presents  on  lateral  view  an  unusually  high  cranium  over- 
towering  a  small,  receding  face,  and  protruding  lower  jaw.  In  front  it 
has  a  narrow  oval  outline  with  high  orbits  and  irregular  teeth. 
(Figs.  14  and  15.) 

Various  measurements  were  made  and  compared  with  the  average  of 
ten  normal  skulls,  and  are  given  in  the  following  table.  The  measure- 
ments are  in  centimetres  unless  otherwise  stated. 

SPECIMEN  AVERAGE 

CRANIUM.                                  SKULL.  SKULL. 

Greatest  length 17.2  18.3 

Greatest  breadth 13.2  14.6 

Cephalic  index 76.7  80.1 

Circumference 49.5  52.6 

Biauricular  distance  over  bregma 35. 

Basio-bregmatic  height 15.  12.4 

Vertical  height  from  external  auditory  meatus  to 

bregma , 13.5  12.1 

Capacity 1450  cc.  1450  cc. 

Basion  to  foramen  caecum 9.7  8.3 

Distance  from  inion  to  vertical  dropped  to  basion 8.  7.9 

Basion  to  spenocribriform  junction,  Huxley's  base 

line.. .                                                                              .6.6  6.4 


*The  skull  was  presented  at  the  fifteenth  annual  session  of  the  Association  of 
American  Anatomists,  at  the  University  of  Chicago,  Dec.  31,  1901  to  Jan.  2, 1902,  and  a 
brief  abstract  was  later  published  in  the  proceedings  of  the  society. 

tL.  Hektoen.  Anatomical  Study  of  a  Short  Limbed  Dwarf,  with  Special  Reference 
toOsteo^euesis  Imperfecta  and  Uhondrodystrophia  Foetalis. — Amer.  Jour.  Med.  Sci.. 
May.  1903. 


34  CHARLES    A.    PARKER 

SPECIMEN       AVERAGE 

SPHENOID.                              SKULL.  SKULL. 
Occipitosphenoidal   synchondrosis  to  spheno  crib- 
riform junction— length  of  spbenoid 4.4  4.3 

Postsplienoid 2.  2.3 

Presphenoid 2.5  2.2 

Pituitary  fossa,  depth 1.  .9 

diameter,  transverse 1.5  1.3 

diameter,  antero-posterior 1.  1.2 

Foramen  magnum,  length 3.7  3.7 

breadth 3.4  3.1 

FACE. 

Basion  to  nasion 10.1  10.1 

Basion  to  posterior  inferior  angle  of  nasal  bone 9.  9.7 

Basion  to  prosthion 7.5  9.6 

Basion  to  gnathion 9.2  11.6 

Basion  to supraorbital  notch 10.  10.2 

Basion  to  middle  of  infraorbital  margin 7.5  8.6 

Basion  to  posterior  nasal  spine 3.7  4. 

Nasion  to  prosthion 6.2  7.1 

Nasion  to  gnathion 10.7  12. 

Nasion  to  gonion 10.5  12.5 

Prosthion  to  gnathion 4.3  

MANDIBLE. 

Gonion  to  gonion 9.  9.9 

Gonion  to  gnathion 6.5  9.1 

PALATE. 

Length 3.4  4.9 

Breadth,  interalveolar 3.7  3.8 

NASAL  CAVITIES. 

Anterior  nares,  height 3.  3.1 

width 2.1  2.3 

Posterior  nares,  height 2.5  2.7 

width 3.5  3. 

The  maximum  length  is  17.2  cm.,  the  maximum  breadth  13.2  cm., 
with  a  corresponding  circumference  of  49.5  cm. 

The  height  from  the  basion,  or  anterior  margin  of  the  foramen  mag- 
num, to  the  bregma,  is  15  cm.  Although  a  comparison  of  these  figures 
with  those  averaged  from  ten  normal  skulls  shows  both  the  breadth  and 
length  to  be  slightly  over  1  cm.  short  of  the  average,  yet  the  height,  which 
is  increased  by  over  2  cm.,  completely  compensates  for  the  circumferen- 
tial constriction,  as  shown  by  the  capacity  of  1450  cc.,  that  of  the  aver- 
age normal  male  skull.  The  cephalic  index  is  76.7,  hence  the  skull  is  of 
the  mesaticephalic  type. 


WORMIAN    BONES  35 

The  internal  surface  of  the  base  presents  little  variation  from  the 
average  sic  a  11  in  form  or  measurements;  the  foramen  magnum  is  normal 
in  size,  shape  and  location,  as  are  also  neighboring  parts  of  the  occipital 
bone,  except  that  the  upper  part  of  the  tabular  portion  is  composed  of 
Wormian  bones. 

The  thickness  varies  from  2  mm.  laterally  in  the  temporal  region,  to 
9  mm.  in  the  frontal  and  occipital,  the  average  being  4  to  5  mm. 

The  distance  from  the  basion  to  the  foramen  caecum  is  1  cm.  above 
the  average,  which,  considering  the  shortness  of  the  skull  and  normal 
location  of  the  basion,  appears  disproportionate,  but  is  explained  by  the 
absence  of  the  frontal  sinus  and  crest.  The  foramen  is  situated  1  to  2 
cm.  nearer  the  anterior  surface  of  the  skull  and  correspondingly  farther 
from  the  basion. 

It  is  not  unusual  to  find  the  distance  from  the  glabella  to  the  fora- 
men more  than  2  cm.,  while  in  this  skull  it  is  less  than  1  cm. 

The  distance  from  the  basion  to  the  occipitosphenoidal  synchon- 
drosis  is  normal,  as  is  also  the  distance  from  the  latter  to  the  anterior 
superior  angle  of  the  sphenoid  at  the  cribriform  suture.  The  cerebral 
surface  of  the  presphenoid  measures  2.5  cm.,  while  the  postsphenoid 
measures  but  2  cm.,  giving  an  index  of  125,  obtained  by  dividing  100 
times  the  former  by  the  latter,  the  average  being  very  close  to  100,  or 
both  parts  equal.  In  a  series  of  skulls  examined  the  maximum  was  113, 
and  the  minimum  87. 

While  the  total  length  of  the  cerebral  surface  of  the  sphenoid  is  not 
affected,  the  disproportion  between  the  two  parts  is  unusual,  and  con- 
stitutes the  only  noteworthy  variation  from  the  ordinary  measurements 
in  this  region. 

Although  somewhat  asymmetrical  in  general  outline,  the  entire 
cranium  presents  but  slight  variations  from  the  normal  measurements, 
the  moderate  circumferential  constriction  being  accompanied  by  vertical 
elongation  with  undiminished  capacity,  and  the  disproportion  between 
the  pre-  and  postsphenoid  making  no  difference  in  the  length  of  the  floor. 

The  peculiar  shape  of  the  skull  with  the  recession  of  the  face  may  be 
represented  by  superimposing  an  outline  of  a  median  section  of  the  skull 
upon  a  similar  outline  of  an  average  skull,  so  that  a  line  from  the  basion 
to  the  sphenocribriform  junction,  the  base  line  of  Huxley,  in  one,  exactly 
corresponds  with  a  similar  line  in  the  other,  their  uppermost  ends  being 
at  the  same  point.  (Fig.  19.) 

RECESSION  OF  FACE: — If  the  facial  profiles  be  represented  by  two 
irregular  curves  drawn  through  the  nasion,  posterior  inferior  angle  of  the 
nasal  bone,  prosthion  and  gnathion,  a  comparison  of  them  will  show  that 
they  lie  quite  near  at  their  upper  ends  at  the  nasion,  and  progressively 
diverge  to  the  prosthion  the  point  of  maximum  separation  of  2.4  cm., 


36  CHARLES    A.    PARKER 

from  whence  they  continue  nearly  parallel  or  slightly  converging  to  the 
gnathion,  where  the  difference  from  the  average  skull  is  about  the  same 
as  at  the  prosthion. 

The  curves  are  obtained  by  joining  the  arc  connecting  the  three 
upper  points  with  that  connecting  the  three  lower  at  their  point  of 
intersection.  (Fig.  20.) 

A  series  of  measurements  from  the  basion  successively  to  the  afore- 
mentioned parts  compared  with  a  similar  series  the  average  of  ten  nor- 
mal skulls  confirms  the  results  obtained  by  direct  comparison  of  profiles 
showing  no  recession  at  the  nasion,  agreeing  with  the  measurements  of 
the  base  of  the  skull,  a  slight  foreshortening  at  the  posterior  inferior 
angle  of  the  nasal,  the  portion  most  commonly  present  of  the  lower 
extremity  of  that  bone,  and  most  marked  at  the  prosthion  where  the 
difference  as  above  stated  is  over  2  cm. 

Although  the  lower  jaw  protrudes  beyond  the  upper,  and  relieves  in 
some  measure  the  appearance  of  recession,  it  also  shares  in  the  general 
defective  development  of  the  face,  and  is  decidedly  shortened,  the 
gnathion,  or  most  prominent  part  of  the  symphysis  menti,  being  2.4  cm. 
nearer  the  basion  than  normally,  and  its  intrinsic  length  from  gonion  to 
gnathion  2.6  cm.  below  the  average. 

A  series  of  horizontal  profiles  drawn  through  the  various  levels  men- 
tioned compared  with  those  of  a  normal  skull  show  in  each  plane  concen- 
tric curves  with  increasing  recession  of  the  lateral  regions  of  the  face 
similar  to  that  in  the  median  line. 

The  vertical  curves  are  eccentric,  the  horizontal  concentric.  There 
is  a  vertical  shortening  of  the  face  of  1.3  cm. 

As  the  face  is  but  slightly  narrowed  the  main  fault  of  development  is 
in  the  sagittal  plane  with  but  little,  if  any,  in  the  coronal,  and  as  the 
recession  is  symmetrical,  affecting  both  sides  of  the  face  alike,  it  is  evi- 
dently the  result  of  some  general  cause  exerting  its  principal  influence  in 
a  sagittal  direction.  The  recession  is  not  due  to  the  premature  ossifica- 
tion of  the  basiosphenoid  cartilage  with  consequent  shortening  of  the 
base  of  the  skull,  as  has  already  been  shown,  nor  to  an  excessive  flexion  of 
the  face  on  the  cranium  from  any  other  possible  cause,  as  the  normal 
distance  separates  the  basion  and  the  posterior  nasal  spine,  the  meeting 
point  of  the  vomer  and  palate  bones,  which  from  their  relation  to  the 
base  of  the  skull  would  be  the  ones  most  influenced  by  its  flexion.  It  is 
therefore  necessarily  due  to  the  changes  in  the  bones  of  the  face  itself, 
and  principally  and  primarily  in  the  maxilla?,  as  the  ones  most  influencing 
its  form.  The  true  facial  profile  is  formed  by  the  nasal  and  maxillary 
bones,  with  the  former  resting  upon  the  superior  maxillae;  so  that  changes 
in  the  latter  affecting  their  nasal  processes  produce  corresponding  varia- 
tions in  the  positions  of  the  nasals,  the  upper  ends  of  which  remain  with 
the  cranium  proper,  wbile  the  lower  ends  follow  the  changes  of  the  ma-x- 


WORMIAN      BONES  37 

illas  and  swing  on  the  upper  as  on  a  pivot.  The  increasing  recession  from 
above  downward  reaching  its  acme  at  the  maxillaa  is  co-ordinate  evidence 
of  the  primary  responsibility  of  these  bones  for  this  feature  of  the  skull. 
As  the  evolution  of  the  teeth  is  the  most  important  factor  in  the 
growth  of  the  jaws,  and  perversions  in  this  process  produce  irregularities 
in  the  development  of  the  maxillas,  a  consideration  of  the  dentition  is 
essential  to  a  proper  appreciation  of  the  maxillary  changes. 

DENTITION. 

SUPERIOR  MAXILLAE. 

Incisors.  The  upper  jaw  contains  two  large,  well  spaced  median  in- 
cisors, and  one  small  lateral  incisor  on  the  right  side,  half  the  normal 
width,  and  separated  from  the  median  by  a  space  equal  to  its  own  width, 

Canines.  The  canines  are  well  developed,  the  left  being  shifted  one 
centimeter  nearer  the  median  line  through  non-development  of  the  lateral 
incisor.  Its  ridge  also  participates  in  the  shifting  and  borders  the  lateral 
margin  of  the  anterior  nares.  The  intermaxillary  suture  is  deflected 
slightly  to  the  left  as  it  approaches  the  alveolar  margin. 

Premolars.  Two  well  developed  and  partially  rotated  premolars  are 
present  on  the  left  side,  and  one,  the  distal,  well  developed  and  partially 
rotated,  on  the  right.  Two  unoccupied  alveoli,  one  lateral  and  one 
medial,  are  present  behind  this  single  premolar,  the  former  probably 
being  for  the  absent  second  premolar,  and  the  latter  of  small  size,  of 
unknown  function. 

Molars.  The  first  molars  only  are  present  on  either  side,  the  second 
and  third  never  having  erupted. 

There  are  six  teeth  on  the  right  side,  and  five  on  the  left.  The  ab- 
sence of  the  left  lateral  incisor  with  mesial  shifting  of  the  canine  is 
accompanied  by  marked  left  sided  flattening,  producing  considerable 
asymmetry  of  the  alveolar  arch.  Vertically  they  are  much  shortened, 
and  the  nasal  processes  separated  from  the  frontal  by  intervening 
Wormian  bones. 

MANDIBLE. 

Incisors.  Two  shallow  alveoli  mark  the  place  of  two  missing  central 
incisors  that  were  of  fair  size,  judging  from  the  space  left  for  them. 

One  lateral  incisor  is  present  on  the  right  side  but  none  on  the  left, 
corresponding  with  the  same  condition  in  the  upper  jaw. 

Canines.  The  two  canines  are  present,  the  left  being  5  cm.  nearer 
the  symphysis  than  the  right. 

Premolars.    The  first  premolars  are  present  on  either  side. 

The  second  premolars  are  absent  on  both  sides. 

On  the  left  side  is  a  narrow  interval  between  the  first  premolar  and 
the  first  molar  with  no  alveolar  absorption;  on  the  right  an  interval  of 


38  CHARLES    A.    PARKER 

two  centimeters  exists  between  the  first  premolar  and  the  second  molar 
with  absorption  of  the  alveolar  process,  which  probably  once  contained  a 
well  developed  second  premolar  and  a  first  molar. 

Molars.  The  first  and  second  molars  are  present  on  the  left  side;  and 
the  second  with  an  erupting  third  on  the  right,  the  first  as  just  men- 
tioned probably  having  formerly  occupied  the  region  of  the  absorbed 
alveolus. 

Counting  the  two  median  incisors  whose  alveoli  are  present,  there  are 
six  teeth  remaining  in  each  lateral  half,  the  total  number  erupted  on 
the  leftside,  while  on  the  right  side  there  were  eight,  the  full  number. 

This  excess  of  the  right  side  over  the  left  of  eight  to  six,  is  similar  to 
that  in  the  upper  jaw,  which  is  as  six  to  five.  As  in  the  upper  jaw,  the 
absence  of  the  left  lateral  incisor,  and  mesial  shifting  of  the  canine, 
determine  a  flattening  of  the  curve  on  the  same  side  accompanied  here 
by  an  abrupt  bend  at  the  canine  tooth.  The  muscles  of  the  cheeks  and 
lips  evidently  were  important  acessories,  producing  the  reciprocal 
changes  in  the  jaws  for  the  articulation  of  the  teeth. 

The  length  of  the  right  half  from  the  symphysis  to  the  posterior 
border  of  the  ramus  exceeds  the  left  by  1  cm.  As  there  is  no  backward 
displacement  of  the  ramus  and  the  normal  curve  is  maintained,  the  in- 
creased length  causes  a  slight  displacement  of  the  symphysis  to  the  left 
of  the  median  line. 

A  slightly  increased  relative  deficiency  over  that  of  the  lower  jaw 
exists  in  the  length  of  the  upper,  corresponding  to  the  more  incomplete 
dentition.  The  distance  between  the  condyles  corresponds  with  the 
normal  measurements  of  the  base  of  the  skull. 

This  study  of  the  dentition  renders  very  apparent  the  role  of  the 
teeth  as  an  important  causative  factor  in  the  production  of  the  facial 
deformity;  and,  as  the  permanent  teeth  are  the  ones  more  evidently  in- 
volved, the  disturbing  process,  doubtless  prenatal  in  origin isseen  to  have 
extended  through  a  considerable  number  of  postnatal  years,  in  this 
respect  corresponding  with  the  changes  occurring  in  the  growth  of  the 
chondro-skeleton  as  shown  in  the  fragile  and  misshapen  bones  of  the 
trunk  and  limbs. 

POSTERIOR  NARES.  The  posterior  nares  measures  2.5  cm.  in  height 
and  3.5  cm.  in  width.  In  the  average  normal  skull  the  two  measurements 
are  practically  equal. 

This  great  disproportion  between  the  height  and  width  of  the  post- 
erior nares  gives  a  broadening  effect,  which  with  the  incomplete  dentition 
already  noticed,  stamps  the  face  anatomically  of  the  infantile  type  ren- 
dering the  general  deformity  particularly  conspicuous  because  of  the 
adult  cranium, 


WOKMIAN    BONES  39 

WORMIAN  BONES. 

By  far  the  most  interesting  feature  of  this  skull  is  the  extraordinary 
development  of  Wormian  bones,  numbering  172.  (Figs.  14,  15,  16,  17, 18.) 

These  bones  are  most  numerous  in  the  posterior  and  lateral  regions 
of  the  skull,  supplanting  the  larger  portion  of  the  parietals,  the  squamous 
portions  of  the  temporals,  and  the  upper  half  of  the  tabular  portion  of 
the  occipital. 

Several  occur  in  the  vertical  and  orbital  plates  of  the  frontal,  partic- 
ularly in  the  vicinity  of  the  nasal  notch.  The  portions  of  the  cranium 
free  from  them  are  the  lower  half  of  the  tabular,  the  condyles  and  basilar 
portions  of  the  occipital,  the  mastoid  and  petrous  portions  of  the  tempo- 
rals, the  sphenoid  and  ethmoid  bones,  or  those  parts  developed  primarily 
from  cartilage,  the  chondro-cranium. 

They  range  in  size  from  3  mm.,  and  even  less  in  the  posterior  and 
lateral  regions,  to  one  measuring  5  by  9  cm.  in  the  upper  part  of  the 
frontal  bone. 

They  are  mostly  irregularly  circular  in  form,  with  coarse  and  fine 
dentations  for  articulation  with  similar  adjacent  bones.  All  layers  of 
the  bones  are  affected,  the  outer  surface  presenting  the  most  irregular 
and  uneven  serrations,  the  inner  showing  fewer  irregularities  combining 
with  the  others,  making  a  smooth,  even  surface  next  the  dura. 

Parietal  bones.  Three-fourths  of  each  parietal  bone  are  represented 
by  various  sizes  of  Wormian  bones,  ranging  in  diameter  from  3  mm.  to 
3cm.,  the  remaining  fourth  consisting  of  a  single  quadrilateral  segment 
measuring  4  by  8cm.,  occupying  the  anterior  superior  angle,  separated 
from  its  fellow  by  the  sagittal  suture,  and  forming  with  the  frontal  the 
upper  part  of  the  coronal  suture.  Bordering  the  coronal  suture  on  either 
side  below  the  larger  segments  are  three  or  four  of  smaller  size  ranging 
from  2  cm.  to  3  cm.  in  diameter.  The  temporal  ridges  are  indistinct  or 
absent.  On  the  inner  surface  the  grooves  for  the  meningeal  arteries  are 
weil  marked.  The  average  thickness  is  3  to  4  mm. 

Temporal  bones.  The  squamae  temporales  consist  almost  entirely  of 
various  sized  Wormian  bones,  their  slender  interlocking  processes  pre- 
senting an  appearance  resembling  a  delicate  pattern  of  lace  work.  As 
previously  mentioned  the  mastoid  and  petrous  are  not  involved. 

Occipital  bom.  The  line  of  separation  between  the  membranous  and 
cartilaginous  portions  of  the  squama  occipitalis  is  distinctly  marked  by  a 
curved  denticulated  suture  extending  from  one  mastoid  region  to  the 
other,  rising  in  the  middle  1}£  cm.  above  the  inion,  corresponding  exactly 
to  the  lower  boundary  of  the  interparietal  bone  as  outlined  by  Broca. 
The  part  above  this  suture  is  composed  entirely  of  Wormian  bones,  as  is 
well  shown  in  the  posterior  view  of  the  skull.  (Fig.  17.) 

Frontalbone.  The  unusually  high  frontal  bone  is  divided  into  two 
nearly  symmetrical  halves  by  the  persistent  metopic  suture.  The  entire 


40  CHARLES    A.    PARKER 

upper  portion  of  the  right  half  exists  as  a  separate  bone,  cut  off  from  the 
lower  part  by  a  suture  extending  from  the  metopic  laterally  to  the  coro- 
nal. This  large  Wormian  bone  is  somewhat  quadrilateral  in  form,  and 
measures  9  cm.  in  length  by  5  cm.  in  width. 

Twelve  small  Wormian  bones  are  located  in  the  suture  between  the 
orbital  plates  and  the  alto  parvie  of  the  sphenoid,  the  cribriform  plate, 
and  lateral  masses  of  the  ethmoid,  the  lachrymal,  and  the  nasal  processes 
of  the  superior  maxillae,  forming  a  considerable  portion  of  the  upper  and 
inner  walls  of  the  orbit.  None,  however,  exists  in  the  nasofrontal  suture. 
The  distribution  by  numbers  in  the  different  regions  may  approximately 
be  given  as  follows: 

Frontal  bone, 12. 

Parietals,  each, 40. 

Temporals,  each,  -       -       -       -       -       -       .       25. 

Occipital, 30. 

Sutures.  The  sagittal  suture  extends  uninterruptedly  from  the  nasion 
to  within  one  and  a  half  centimeters  of  the  inion,  or  throughout  the 
total  median  extent  of  the  membranous  cranium,  a  condition  normally 
present  only  in  intrauterine  life. 

This  suture  is  quite  distinct  throughout,  the  Wormian  bones  that 
border  i t  for  the  greater  part  of  its  extent  not  attempting  to  cross  it 
more  than  the  usual  dentations  common  to  the  normal  suture.  In  the 
frontal  region  its  dentations  are  least  developed,  towards  the  lower  part 
becoming  a  sutura  harmonia. 

The  persistence  of  the  frontal  portion  of  the  sagittal  suture  is  of  very 
frequent  occurrence,  but  its  persistence  through  the  membranous  por- 
tion of  the  squama  occipitalis  is  exceedingly  rare,  when  present  being 
almost,  if  not  quite  always,  accompanied  by  a  bisected  interparietal. 

The  coronal  suture  is  well  marked  and  bounded  behind  by  Wormian 
bones  from  one  temporal  fossa  to  the  other. 

The  squamoparietal  suture  is  completely  obliterated  by  the  confusion 
of  Wormian  bones  in  its  vicinity,  and  the  sphenoparietal,  squamosphe- 
noidal  and  mastoparietal  sutures  are  only  defined  by  the  limitation  of 
development  of  these  supernumerary  bones  at  the  borders  of  the  great 
wing  of  the  sphenoid  and  mastoid  portion  of  the  temporal,  as  these  are 
the  lines  of  separation  between  the  membranous  and  thechondrocranium. 

The  lambdoid  suture  is  also  obliterated,  as  it  is  impossible  to  trace  it 
with  any  degree  of  precision  through  the  mosaic  of  bones  occupying  this 
region. 

As  before  mentioned,  a  well  marked  suture  extends  in  a  curved  direc- 
tion from  one  mastoid  region  to  the  other,  crossing  the  center  of  the 
occipital  just  above  the  inion,  marking  out  the  lower  limit  of  develop- 
ment of  Wormian  bones,  or  the  separation  in  this  region  of  the  membra- 
nous and  chondro-  or  primordial  cranium. 


WORMIAN    BOXES 


41 


The  adventitious  suture  extending  from  the  metopic  to  the  coronal, 
and  separating  the  large  Wormian  bone  from  the  right  half  of  the  fron- 
tal, is  long  enough  to  merit  special  mention.  It  is  reciprocally  bevelled 
and  feebly  denticulated. 

The  rest  of  the  cranial  sutures  are  distinct,  though  a  number  of 
Wormian  bones  are  intercalated  in  those  surrounding  the  nasal  notch  of 
the  frontal. 

Fontanelles.  As  the  whole  squamae  temporales  and  adjacent  portions 
of  the  parietals  consist  of  Wormian  bones,  it  is  impossible  to  separately 
distinguish  pterion  and  asterion  ossicles. 

A  similar  profusion  of  these  bones  in  the  posterior  region  of  the  skull 
makes  it  equally  impossible  to  distinguish  an  os  Wormien  lamdatique  in  the 
posterior  fontanelle.  This  complication  does  not  exist  at  the  bregma, 
where  no  bregmatic  bone  is  present. 

In  each  orbit  there  is  an  os  Wormien  orbitaire  occupying  the  angle  of 
junction  of  the  frontal,  os  planum  of  the  ethmoid  and  lesser  wing  of  the 
sphenoid. 


FIG.  21.— Right  orbit, 
fontanelle. 


A,  B,  C,  I.  D.  Wormian  bones;  A,  occupying  the  orbital 


The  one  in  the  right  orbit  measures  1  cm.  wide  by  2  cm.  long,  the 
long  axis  being  obliquely  vertical.  (Fig.  21.)  The  one  in  the  left  orbit 
measures  7  mm.  by  12  mm.  and  has  the  same  relative  direction  as  the 
right.  (Fig.  22,  page  42.) 

This  bone  was  not  observed  a  single  time  in  the  nearly  500  skulls 
examined  by  Chambellan. 

In  the  accompanying  figures  are  shown  other  accessory  bones  in  the 
orbits,  four  being  visible  in  the  right,  and  three  in  the  left  in  the  suture 
surrounding  the  nasal  notch. 


42  CHARLES    A.    PARKER 

In  the  so-called  abnormal  fontanelles  at  the  site  of  the  nasof rental 
suture,   the  fontanelle  glabellaire,  and  at  the  obelion,   the  fontanelle 


FIG.  2:2.— Left  Orbit.  A,  B,0,  D,  Wormian  bones;  A,  occupying  theorbital  fontanelle. 

obelique,  no  example  can  be  said  to  be  present;  in  the  tirst  instance  being 
definitely  absent,  and  in  the  second,  although  the  number  of  adventitious 
bones  apparently  leaves  some  room  for  doubt,  none  crosses  the  sagittal 
suture,  demonstrating  here  also  the  absence  of  a  special  bone,  or  true 
os  Wormien  obeliqw. 

Although  so  much  of  the  cranium  is  composed  of  Wormian  bones,  yet 
the  cranial  anlage  are  well  preserved,  the  principal  sutures  and  bony 
areas  being  present  and  in  their  proper  relations,  showing  that  whatever 
general  influences  affected  the  skeleton,  they  were,  in  the  skull  at  any 
rate,  limited  to  osteogenesis,  and  not  of  earlier  origin  or  farther  reaching 
in  their  effects  disturbing  the  fundamental  elements  and  interfering 
with  the  type  of  development  as  is  observed  in  the  perverted  chondro- 
genesis  of  chondrodystrophia  foetalis,  and  frequently  seen  in  monsters. 

The  same  may  be  said  of  the  rest  of  the  skull;  all  the  bones  are  pres- 
ent with  their  usual  relations  though  the  imperfect  development  of 
some  produces  considerable  deformity,  most  marked  in  the  recession  of 
the  face. 

No  similar  condition  in  an  adult  skull  has  been  recorded,  and  but  two 
of  a  like  nature  have  been  observed  in  infants.  These  are  the  cases  of 
Jung  and  Vrolik.  Quoting  from  Hrdlicka,  (%Jung  published  in  1827  an 
observation  on  the  skull  of  a  new  born  male  child,  which  showed,  besides 
an  extreme  number  of  Wormian  bones,  irregular  divisions  in  both  parie- 
tals.  The  right  bone  was  separated  into  five,  the  left  into  three  por- 


WORMIAN    BONES  43 

tions,"  and  in  referring  to  the  same  instance,  Zeller  remarks,  ''Jung  says 
the  disintegration  of  the  whole  cranium  into  intercalary  bones  is  very 
rare." 

In  regard  to  the  second  case,  Vrolik  says,  "The  skeleton  is  from  anew 
born  infant  of  syphilitic  parents. 

"It  died  the  third  day;  the  following  year  the  mother  bore  a  healthy 
child.  The  whole  osseous  system  was  vitiated.  This  was  most  noted  in 
the  cranium,  where  no  bone  could  be  said  to  be  intergrate.  The  frontal 
bone,  the  parietal  bones,  for  the  most  part,  and  also  the  occipital  bone, 
consisted  of  very  many  nuclei  with  irregular  bones,  which  were  joined 
by  serrate  margins,  and  gave  to  the  cranium  the  appearance  of  being 
composed  of  very  many  little  Wormian  bones  put  together. 

'•Without  doubt 
the  cranium  was 
expanded  by  hy- 
drocephalous  with 
a  short  and  nar- 
row face.  The 
rest  of  the 
skeleton  showed 
an  imperfect 
state  of  the  osse- 
ous system,  with 
many  fractures 
occupying  all  the 
ribs  and  long 
bones,  some  re- 
cent, some  cured 
by  callus.  No 
doubt  this  was 

FIG.  23. — Osteogenesis  imperfecta  cranii.     (After  Vrolik.)          from     imoerfecfc 

osteogenesis,  both  as  to  form  and  texture  of  the  bones." 

The  accompanying  figure  shows  this  infantile  skull  with  its  rich 
mosaic  of  supernumerary  ossiflc  nuclei  to  be  an  almost  perfect  minature 
of  the  one  presented  with  this  article.  (Fig.  23.) 


44  CHARLES    A.    PARKER 

GENERAL    SUMMAEY. 
CHAMBELLAN'S  CONCLUSIONS. 

Chambellan  at  the  close  of  his  exhaustive  work  presents  the  follow- 
ing conclusions: 

The  real  name  of  Olaus  Wormius  is  Olaiis  Worm. 
We  may  establish  two  categories  of  Wormian  bones. 

(1)  The  os  Wormien  suturaux. 

(2)  The  os  Wormien  fontanellaires. 

The  os  epactal  and  os  interparietal  should  still  be  considered  as 
different  bones. 

There  are  more  Wormian  bones  in  the  lambdoid  suture  than  in  the 
others;  they  are  also  here  the  most  voluminous.  Following  in  order  of 
frequency  are  the  coronal,  sagittal,  squamous,  masto-occipital  and  masto- 
parietal. 

There  are  occasionally  met  in  the  sagittal  suture  certain  Wormian 
bones  of  quite  considerable  size,  and  occupying  always  a  place  in  the 
vicinity  of  the  bregma,  the  obelion,  or  the  lambda.  In  consequence  they 
should  be  given  the  names  os  parabregmatique,  paraobelique  and  para- 
lamdatique,  or  better,  sagittal-lambdoidien. 

The  skulls  with  obliterated  sutures  contain  fewer  Wormian  bones 
than  those  in  which  the  sutures  are  open  or  present. 

There  are  more  Wormian  bones  on  the  right  side  than  on  the  left. 

The  Wormian  bones  are  developed  in  two  ways;  the  first,  the  usual 
manner,  by  the  development  of  separate  ossific  nuclei,  the  second,  by  the 
absorption  of  pedicles  of  denticules  leaving  the  minute  extremities  free. 

In  general  they  are  more  numerous  in  the  larger  crania. 

This  appears  constant  in  all  the  groups  examined,  Auvergnats, 
Parisians,  Neo-Caledonians,  Negroes,  Incas,  microcephales,  hemi-micro- 
cephales,  apes  and  hydrocephales. 

They  are  more  numerous  in  brachycephales  than  in  dolichocephales. 
This  is  notable,  as  the  former  have  a  greater  average  capacity  than  the 
latter. 

In  the  Parisians,  Auvergnats,  Neo-Caledonians,  Negroes,  and  Incas 
they  are  more  abundant  on  the  right  side  than  on  the  left. 

HYRTL'S  RULES. 

Hyrtl  gives  the  following  rules: 

(1)  They  are  found  only  in  the  cranium,  and  more  in  the  true  than 
in  the  false  sutures.  In  the  face  but  two  examples  have  been  personally 
observed,  one  in  the  crucial  suture  of  the  palate,  the  other  in  the  inter- 
nasal  suture. 


WOBMIAN    BONES  45 

(2)  They  are  more  frequent  in  large  skulls  than  in  small. 

(3)  Their  size  varies  from  a  flax  seed  to  that  of  a  dollar,  which  was 
observed  in  the  anterior  fontanelle. 

(4)  Paired  Wormian  bones  on  the  cranial  vault  are  more  frequently 
symmetrical  than  not,  but  in  the  temporal  fossa  are  as  often  asymmetri- 
cal as  otherwise. 

(5)  The/ coasist  usually  of  two  layers  with  diploe,  their  inner  sur- 
face as  a  rule  being  smaller  than  the  outer. 

(6)  Rarely  they  are  found  on  the  inner  surface  and  not  on  the  outer, 
more  frequently  do  they  appear  only  on  the  outer  surface  when  they  are 
always  small.     A  rare  form  is  the  os  insulare  observed   in  the  parietal 
near  the  margo  squamosa. 

AUTHOR'S  CONCLUSION*. 

Wormian  bones  are  properly  named  after  Olaiis  Worm,  and  his  claim 
to  priority  of  description  is  established  by  his  letter  to  Thomas  Bartholin. 

To  the  two  categories  of  Cliarnbellan  should  be  added  the  os  insules 
of  Manouvrier  and  Ilyrtl. 

The  os  interp;irietal  should  be  limited  to  those  single,  or  rarely 
several,  elements  representing  the  complete  anlage  of  the  membranous 
squama  occipitalis. 

The  os  Inca  of  Rivero  and  Tschudi  is  identical  with  the  true  inter- 
parietal;  but  the  os  epactal  and  os  Inca  as  commonly  defined  have  no 
definite  morphological  limits,  and  therefore  no  absolutely  distinctive 
characteristics. 

All  observers  agree  to  the  preponderance  of  Wormian  bones  in  the 
lambdoid  suture.  Their  almost  complete  limitation  to  the  sutures  bor- 
dering the  parietal  bones  is  also  noteworthy. 

They  develop  either  from  original  centres  themselves  or  by  segrega- 
tion from  pre-existing  centres. 

They  vary  in  size  from  a  millimetre  in  diameter  to  the  one  measuring 
5  cm.  by  9  cm.  in  the  accompanying  skull,  probably  the  largest  true 
Wormian  bone  ever  recorded. 

They  are  frequent  in  the  crania  of  infants,  and  at  times  are  doubt- 
less synchronous  in  origin  with  the  normal  ossiflc  centres. 

The  obliteration  of  the  sutures  by  age  or  other  causes  diminishes 
their  number  by  effacing  the  characteristic  feature  that  distinguishes 
them  from  the  adjacent  bones. 

True  Wormian  bones  have  no  morphological  value. 

Their  increased  frequency  in  crania  of  large  capacity  is  an  apparently 
well  established  fact,  the  same  rule  applying  whether  enlarged  from 
physiological  or  pathological  causes. 

Brachycephalic  skulls  have  the  greatest  total  sutural  lengths.  With 
Chatnbellan's  observations  that  the  brachycephalic  skulls  have  the 


46  CHARLES    A.    PARKER 

greatest  average  capacity  and  the  largest  number  of  Wormian  bones, 
this  establishes  a  direct  ratio  between  the  number  of  Wormian  bones, 
and  the  total  sutural  length. 

In  the  50  skulls  examined  by  the  writer  the  total  dextral  considerably 
exceeded  the  total  sinistral  sutural  length.  As  Chambellan  observed  a 
dextral  preponderance  of  Wormian  bones  in  the  skuils  he  examined, 
their  excess  on  the  right  side  further  evidences  the  relation  between  the 
sutural  length  and  the  frequency  of  these  bones. 

Incidental.  There  is  a  definite  increase  in  length  of  the  coronal 
suture  in  brachycephalic  skulls,  and  a  slightly  diminished  length  of  the 
lambdoid  and  sagittal  sutures.  The  lateral  or  squamous  length  shows  a 
progressive  increase  from  dolichocephales  to  brachycephales. 

The  great  majority  of  Wormian  bones  are  physiological  in  origin  and 
compensatory  in  nature,  and  only  when  presenting  distinctly  unusual  or 
abnormal  features  should  a  pathological  origin  be  considered. 

There  are  but  three  recorded  cases  in  which  Wormian  bones  are 
reputed  to  have  exerted  a  pathological  influence,  causing  still-birth  of 
the  fetus  in  each  of  the  reported  instances. 

The  case  reported  in  this  article  is  unique. 


BONES  47 


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WORMIAN    KONES 


PLATK  I 


Fm.  14. — FRONT  VIEW 


CHARLES  A.  PARKER 


WOK  MIAN  BOXES 


PLATE  II 


FIG.  15.— LATERAL,  VIEW. 


CHARLES  A.  PARKER 


WOKMIAN  BONES 


PLATE  III 


FIG.  16.— LATERAL  VIEW 


CHARLES  A.  PARKER 


WORMIAX  BONES 


PLATE  IV 


FIG.  17. — POSTERIOR  VIEW 


CHARLES  A.  PARKER 


WOKMIAN  BOXES 


PLATE  V 


FIG.  18. — VIEW  OF  VERTEX. 


CHARLES  A.  PARKER 


WOKMIAN   BONES 


PLATE  VI 


FIG.  19 


SUPERIMPOSED  OUTLINES  OF  Two  SKULLS  WITH  THE  LINE  ab  COM- 
MON TO  BOTH;  THE  PRESENT  SKULL  BEING  REPRESENTED  IN  BLACK, 
THE  NORMAL  SKULL  IN  RED. 


CHARLES  A.  PARKER 


WORMIAN    HONES 


I'LATK    VII 


FIG.   20 


COMPARISON  OF  FACIAL  PROFILES.  THE  HEAVY  BLACK  LINE  REPRE- 
SENTING THAT    OF  THE  PRESENT  SKULL.   THE   HEAVY    RED    LlNE  THAT 

OF  A  NORMAL  SKULL. 
CHARLES  A.  PARKEB 


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